民國五十七年，國民義務教育延長為九年。斯時，頭份鎮工商繁榮，學齡人口遽增，本校在政府與地方熱心教育人士配合下，擇定現址（頭份鎮新華里中正一路四零一號）為校址。由三灣國中校長劉漢源先生兼任籌備主任進行擘劃創校工作，並於五十七年八月一日借斗煥、僑善兩國小校舍正式開學。校名訂為『苗栗縣立興華國民中學』，聘呂榮泉先生擔任首任校長。
民國五十七年十一月二十九日，首期校舍完成，是日訂為校慶日。本校學區幅員遼闊，就學人數逐年增加，校舍硬體設備不斷擴充，學校規模由創校的八班逐年發展，學校編制亦逐年增加，由教導﹑總務二處擴充為教務﹑學務﹑總務、輔導處及人事﹑會計二室，行政組織更趨完整。民國八十四年配合政府照顧失學民眾，開設國中補校，招收國小畢業已逾國中學齡之回流生一班；同年，配合教育部技藝教育政策，設立『美容美髮』及『汽車修護』技藝中心，接受鄰近國中推薦，實施相關技藝教學。同時響應『高中社區化』的潮流，爭取設立完全中學來照顧中港溪學子，於八十六年八月奉准改為『苗栗縣立興華中學』，除原有國中規模外，每年招收高中學生四班，並增設圖書館的編制；次又成立國中美術班，延續學區國小美術專長學生的潛能開發。八十九年高中部增設體育班一班，國中部增設資源班，輔導體育專長及弱勢學生；至民國九十年八月一日再度改制為『苗栗縣立興華高級中學』。
創校初期，篳路藍縷，披荊斬棘；呂校長在任十二年半，民國六十九年三月任滿他調，由張國文先生接任，張校長相繼完成照明給水工程，興建文化走廊，舉辦全縣示範觀摩，比賽成績斐然，七十三年九月任期屆滿，由顧海濱校長繼任，顧校長推動學校家庭化，生活倫理化，先後完成五育亭、六藝亭﹑天橋等工程。
民國七十六年九月黃文宏先生接任後，承續前三任的良好基礎，加強生活教育﹑提高讀書風氣﹑改進教學方法﹑籌募教育基金，奠定學校向前發展的根基。民國八十三年二月黃德慶先生繼任，秉持勤儉治校原則，帶領學校轉型成高中，興建高中大樓﹑技藝大樓﹑老師宿舍﹑美藝大樓，更積極籌建圖書館，中港溪畔一所全方位的學府已然成型。
民國九十三年二月陳鎮祥承續校務，調整辦公處所，消除校園死角，致力落實生活教育；全力推動教學正常化，藉以提昇教育成效；更積極爭取經費美化綠化，活化境教功能。
民國九十六年八月一日縣府遴派魏早炯校長接掌本校，魏校長上任後秉持主動、積極、倡導、關懷的態度，加強生活暨人權民主法治教育，落實導師責任制，發揚校園倫理，建立有紀律的校園。為提昇教學品質暨行政效能，鼓勵教師進修，充實各班視聽教學設備，爭取資源改善教學環境，整體規劃前中庭美化綠化校園，積極落實推動小班教學精神，不放棄任何一位學生的理念，明訂友善、健康、創新、卓越學校願景。發展學校特色，期望建立優質的學習環境，培養學生的良好讀書風氣暨健全人格。於民國一○○年間完成與亞太創意技術學院、育達商業科技大學之社區學院策略聯盟。
民國一百年八月一日鄒義昌校長接續校務，以明確的態度及慈悲之心明示四大教育理念：安全成長、思考學習、快樂生活、全人發展並提出自我超越、團隊共識、關懷生命、永續發展為學校四大願景；校長並以傳承創新、熱忱喜好、成就尊嚴、感恩回饋來鼓舞全體教職員工營造興華為一生命共同體之目標。又因應12年國教上路，校長更以精確的前瞻思維提出國立大學保證班及未來領袖培育搖籃為全體師生努力之方向，並積極與社區大學—亞太創意技術學院、育達商業科技大學、大華技術學院等院校進行策略聯盟，展開一連串積極之互動。目前正在擘劃第一棟大樓拆除及重建鉅大工程，冀能呈現恢弘大氣、規模雄偉之高中校園形象。
民國一百零參年十二月二十四日本校國中部行政大樓落成啟用，新校舍榮獲教育部補助1億元，縣府配合2,602萬元，共興建地上4層地下1層共25個空間，包含行政辦公室、專科教室、學生教室等以人為本的概念，以建築空間活潑化、
展現校園主題性、新舊紋理的延續三大特色為目標，融合學校歷史文化，外觀採用抿石子建材，採簡約素雅風格，並考量師生教學動線、日照採光、改善西曬、通風等因素，營造和諧完善的學習空間。前縣長劉政鴻、 立委徐耀昌、縣議員羅雪珠、頭份鎮長徐定楨、校長鄒義昌等人一同出席剪綵，現場並安排學校成立的龍舞興華舞龍隊熱鬧慶祝，全體師生也以辦喜事的心情開心迎接新校舍的落成。
此外，為使高中部學生能夠獲得更完整的學習成效，本校獲教育部國教署核定自105學年度起可不再辦理綜合高中部，同時並獲苗栗縣政府教育處核定自105學年度起招收普通科3班、商業經營科1班、資料處理科1班。期能藉由高中的學術涵養與高職的專業技能等發展特質，雙管齊下，共創興華的大未來。本校自創校以來，承蒙地方仕紳大力支持及各界不吝鞭策，興華全體師生必戮力以赴，型塑山城的優質學府與社區共存共榮。
In accordance with Taiwan’s nine-year compulsory education system, Hsing-Hua Junior High School located in Toufen Miaoli County, was founded in 1968. At that time, Toufen was a very prosperous town with a growing school age population. With the cooperation of the government and local enthusiastic educators, the team chose the current location to establish the school.
The school’s location was a part of the Toufen Shrine which dates back to the Japanese colonial rule period. During Japanese colonial rule, local Taiwanese needed to assimilate to Japanese culture while Japan strengthened their imperialism movement and built many shrines throughout Taiwan. Toufen Shrine was located at the junction of Qiao-shan Elementary School and Hsing-Hua Junior High School. Currently, Hsing-Hua’s stadium is on the site of the former shrine’s social affairs office. Due to the hilly terrain, the open space in front of the shrine overlooks Zhunan, Toufen, and Zaoqiao townships. This was the main reason the Japanese chose this location for the shrine. After Taiwan’s transfer of sovereignty from Japan, Qiao-shan Elementary School was built in 1964 and Hsing-Hua Junior High School was founded in 1968.
Adjacent to Toufen Backyard Garden where locals can walk, relax and enjoy the nature, the school has a splendid environment with a beautiful view of green hills, farmlands and tea gardens. Looking out from the classrooms of senior high division, you will catch sight of the breathtaking landscape.
Hsing-Hua has a history of over fifty-two years since its establishment. During its inception the school only enrolled junior high students; however, in 1997 the school was approved to have a high school division. In the beginning the school only had eight classes. Currently, It is a school composed of both junior high and senior high divisions. In the junior high division, there are 23 classes in total. They are Normal Program, with 20 classes from Grade 7th to Grade 9th and Fine Art Program, with 3 classes from Grade 7th to Grade 9th. In the high division, from Grade 10th to Grade 12th, there are 20 classes in total, Three programs are included in the senior division: Normal Program, Vocational Program and Athletic Program. In Vocational Program, it is divided into Business Affairs section and Data Processing section. In general, the total number of students is about 1,200 and the faculty members is about 120. Starting at the new semester of 2021, a mathematics and science experimental class will be added to the high school division. The school is the only public high school in northern Miaoli County with a vocational Program and junior high division.
