“九(jiu)年(nian)(nian)(nian)一(yi)貫(guan)制(zhi)”學(xue)(xue)校，通(tong)常(chang)是指該校的(de)小(xiao)學(xue)(xue)和初(chu)(chu)中(zhong)施行一(yi)體化(hua)的(de)教育(yu)，小(xiao)學(xue)(xue)畢業后可直升(sheng)本校初(chu)(chu)中(zhong)，“小(xiao)升(sheng)初(chu)(chu)”原則(ze)上不(bu)許(xu)擇校流(liu)動，希望在本校升(sheng)初(chu)(chu)中(zhong)的(de)學(xue)(xue)生也不(bu)用為上初(chu)(chu)中(zhong)費盡(jin)心思；九(jiu)年(nian)(nian)(nian)一(yi)貫(guan)制(zhi)學(xue)(xue)校的(de)年(nian)(nian)(nian)級(ji)通(tong)常(chang)被稱(cheng)為1年(nian)(nian)(nian)級(ji)、2年(nian)(nian)(nian)級(ji)……，至9年(nian)(nian)(nian)級(ji)。這樣在學(xue)(xue)生年(nian)(nian)(nian)齡較小(xiao)，適(shi)應能力較弱的(de)時候的(de)教育(yu)會有一(yi)個連貫(guan)性。

"十(shi)二(er)年(nian)(nian)一(yi)貫制學(xue)(xue)(xue)(xue)(xue)校(xiao)(xiao)"是(shi)(shi)指集小(xiao)學(xue)(xue)(xue)(xue)(xue)、初中(zhong)(zhong)和(he)高中(zhong)(zhong)為一(yi)體(ti)的12年(nian)(nian)一(yi)貫制學(xue)(xue)(xue)(xue)(xue)校(xiao)(xiao)。學(xue)(xue)(xue)(xue)(xue)校(xiao)(xiao)主(zhu)要有三個特點，一(yi)是(shi)(shi)連貫性(xing)，學(xue)(xue)(xue)(xue)(xue)生可以從從一(yi)年(nian)(nian)級(ji)(ji)至十(shi)二(er)年(nian)(nian)級(ji)(ji)，相繼完成小(xiao)學(xue)(xue)(xue)(xue)(xue)至高中(zhong)(zhong)教育，其間不間斷、不選拔(ba)。二(er)是(shi)(shi)就近入(ru)學(xue)(xue)(xue)(xue)(xue)、取消招生考試。小(xiao)升初直接升入(ru)本校(xiao)(xiao)初中(zhong)(zhong)和(he)高中(zhong)(zhong)，不必再受小(xiao)升初、中(zhong)(zhong)考折磨之苦。三是(shi)(shi)實行(xing)統(tong)一(yi)的學(xue)(xue)(xue)(xue)(xue)校(xiao)(xiao)行(xing)政、教育、教學(xue)(xue)(xue)(xue)(xue)管理。

“完全中(zhong)學(xue)(xue)(xue)”既(ji)有(you)初級中(zhong)學(xue)(xue)(xue)的(de)學(xue)(xue)(xue)段(duan)，又有(you)高級中(zhong)學(xue)(xue)(xue)學(xue)(xue)(xue)段(duan)的(de)學(xue)(xue)(xue)校，是一(yi)種學(xue)(xue)(xue)校制度。

初中屬于9年義(yi)務教(jiao)育階(jie)段，而高(gao)中不(bu)屬于義(yi)務教(jiao)育，在(zai)學(xue)校的(de)設置中，已(yi)經有(you)許多完全(quan)中學(xue)脫(tuo)鉤為兩所學(xue)校。

許多中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)同時設(she)立初中(zhong)(zhong)(zhong)(zhong)(zhong)部及高中(zhong)(zhong)(zhong)(zhong)(zhong)部，這些中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)就是完全(quan)中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)。不過，國(guo)(guo)家(jia)規(gui)定(ding)國(guo)(guo)家(jia)級重點(dian)中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)和省級重點(dian)中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)不許開(kai)設(she)初中(zhong)(zhong)(zhong)(zhong)(zhong)，但是還是有一些學(xue)校(xiao)違規(gui)操作(zuo)。有一些重點(dian)中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)通過開(kai)辦分校(xiao)等形式開(kai)設(she)初中(zhong)(zhong)(zhong)(zhong)(zhong)，規(gui)避這一規(gui)定(ding)。由于歷史的(de)原因，一些曾(ceng)經開(kai)設(she)初中(zhong)(zhong)(zhong)(zhong)(zhong)但后來取消(xiao)了初中(zhong)(zhong)(zhong)(zhong)(zhong)部或者(zhe)不直接開(kai)設(she)的(de)，仍然被稱(cheng)為(wei)完全(quan)中(zhong)(zhong)(zhong)(zhong)(zhong)學(xue)。