該保護區地(di)(di)理位置為(wei)(wei):東(dong)經126°35′~128°02′,北(bei)緯42°06′~43°51′。總面(mian)積(ji)約114.5萬公頃。其(qi)(qi)中(zhong)林地(di)(di)82.3萬公頃,占總面(mian)積(ji)71.9%;水域(yu)5.7萬公頃,占總面(mian)積(ji)的5.0%。三(san)湖保護區地(di)(di)處長白山(shan)(shan)(shan)余脈(mo)。四(si)面(mian)環山(shan)(shan)(shan),西面(mian)是(shi)吉林哈(ha)達(da)嶺(ling)山(shan)(shan)(shan)脈(mo),北(bei)面(mian)是(shi)老爺嶺(ling)山(shan)(shan)(shan)脈(mo),東(dong)面(mian)是(shi)威虎嶺(ling)和黃泥(ni)嶺(ling)山(shan)(shan)(shan)脈(mo),南面(mian)是(shi)老嶺(ling)山(shan)(shan)(shan)脈(mo)。地(di)(di)勢(shi)東(dong)南高西北(bei)低。地(di)(di)貌(mao)多(duo)(duo)為(wei)(wei)中(zhong)(高)山(shan)(shan)(shan)?低(丘)山(shan)(shan)(shan)?崗(gang)(臺)川(chuan)類。其(qi)(qi)面(mian)積(ji)比例大致為(wei)(wei)七(qi)山(shan)(shan)(shan)二崗(gang)一川(chuan)。境(jing)內山(shan)(shan)(shan)巒(luan)起(qi)伏,綿延不斷,溝壑縱橫,異(yi)峰突兀。海拔800米以上的山(shan)(shan)(shan)峰有80余座(zuo),其(qi)(qi)最(zui)高為(wei)(wei)南樓山(shan)(shan)(shan),海拔1404.8米,在樺甸市常山(shan)(shan)(shan)境(jing)內;最(zui)低為(wei)(wei)豐滿壩下,海拔約190米。該地(di)(di)區地(di)(di)質構成(cheng)多(duo)(duo)為(wei)(wei)玄武巖(yan)、石(shi)灰巖(yan)、土壤(rang)類型為(wei)(wei)暗棕壤(rang)、白漿(jiang)土、草甸土、棕色森林土、泥(ni)炭土等。
三(san)湖保護區處于(yu)北溫(wen)(wen)帶大(da)陸性(xing)季(ji)(ji)風(feng)氣(qi)候區內。四季(ji)(ji)分明,年(nian)(nian)(nian)、日較差大(da)。春季(ji)(ji)干燥(zao)多(duo)風(feng)?夏季(ji)(ji)溫(wen)(wen)熱多(duo)雨?秋(qiu)季(ji)(ji)晴爽(shuang)?冬季(ji)(ji)嚴(yan)寒?年(nian)(nian)(nian)平(ping)均(jun)(jun)氣(qi)溫(wen)(wen)在1.9℃~4.4℃之間(jian)?極端(duan)高溫(wen)(wen)36.6℃,極端(duan)低溫(wen)(wen)-45℃。年(nian)(nian)(nian)≥10℃積溫(wen)(wen)為1900℃~2800℃,并呈(cheng)由南至北增(zeng)加(jia)趨勢?年(nian)(nian)(nian)日照時數2350~2450小時?年(nian)(nian)(nian)降(jiang)水(shui)量由南向北略有減少,為834~673毫(hao)米(mi)之間(jian)。無霜期(qi)大(da)致為110~130天。一月平(ping)均(jun)(jun)氣(qi)溫(wen)(wen)約為-18℃,七月平(ping)均(jun)(jun)氣(qi)溫(wen)(wen)約為20℃左右。該區夏季(ji)(ji)盛行西南風(feng),冬季(ji)(ji)盛行西北風(feng)。
保(bao)護區由于受到(dao)三個湖泊(bo)及森(sen)林等因素影響,又具有湖泊(bo)氣(qi)候(hou)、谷地氣(qi)候(hou)和森(sen)林氣(qi)候(hou)的復(fu)合特征。