該(gai)(gai)保(bao)護區地(di)(di)(di)理位置(zhi)為(wei):東(dong)經(jing)126°35′~128°02′,北(bei)(bei)緯42°06′~43°51′。總(zong)面(mian)(mian)積(ji)約114.5萬公頃(qing)。其中林(lin)(lin)地(di)(di)(di)82.3萬公頃(qing),占(zhan)總(zong)面(mian)(mian)積(ji)71.9%;水(shui)域5.7萬公頃(qing),占(zhan)總(zong)面(mian)(mian)積(ji)的(de)5.0%。三湖保(bao)護區地(di)(di)(di)處(chu)長(chang)白山(shan)(shan)(shan)(shan)(shan)余脈(mo)。四面(mian)(mian)環(huan)山(shan)(shan)(shan)(shan)(shan),西(xi)面(mian)(mian)是(shi)吉林(lin)(lin)哈達嶺(ling)山(shan)(shan)(shan)(shan)(shan)脈(mo),北(bei)(bei)面(mian)(mian)是(shi)老(lao)爺嶺(ling)山(shan)(shan)(shan)(shan)(shan)脈(mo),東(dong)面(mian)(mian)是(shi)威(wei)虎嶺(ling)和黃泥嶺(ling)山(shan)(shan)(shan)(shan)(shan)脈(mo),南面(mian)(mian)是(shi)老(lao)嶺(ling)山(shan)(shan)(shan)(shan)(shan)脈(mo)。地(di)(di)(di)勢東(dong)南高西(xi)北(bei)(bei)低。地(di)(di)(di)貌多(duo)為(wei)中(高)山(shan)(shan)(shan)(shan)(shan)?低(丘)山(shan)(shan)(shan)(shan)(shan)?崗(gang)(臺)川(chuan)類(lei)。其面(mian)(mian)積(ji)比例大致(zhi)為(wei)七山(shan)(shan)(shan)(shan)(shan)二崗(gang)一川(chuan)。境內山(shan)(shan)(shan)(shan)(shan)巒起伏,綿延不斷(duan),溝壑縱橫,異峰突(tu)兀。海(hai)拔(ba)800米以(yi)上的(de)山(shan)(shan)(shan)(shan)(shan)峰有80余座(zuo),其最高為(wei)南樓山(shan)(shan)(shan)(shan)(shan),海(hai)拔(ba)1404.8米,在樺甸市常(chang)山(shan)(shan)(shan)(shan)(shan)境內;最低為(wei)豐(feng)滿壩下,海(hai)拔(ba)約190米。該(gai)(gai)地(di)(di)(di)區地(di)(di)(di)質構成多(duo)為(wei)玄武巖、石灰巖、土(tu)壤(rang)類(lei)型為(wei)暗棕壤(rang)、白漿土(tu)、草甸土(tu)、棕色森林(lin)(lin)土(tu)、泥炭土(tu)等。
三湖保護區處于北(bei)(bei)溫(wen)(wen)(wen)帶大陸(lu)性季(ji)(ji)風(feng)(feng)氣(qi)(qi)候區內。四季(ji)(ji)分明,年(nian)(nian)、日較差大。春(chun)季(ji)(ji)干燥多風(feng)(feng)?夏(xia)(xia)季(ji)(ji)溫(wen)(wen)(wen)熱(re)多雨?秋(qiu)季(ji)(ji)晴(qing)爽?冬季(ji)(ji)嚴寒?年(nian)(nian)平均(jun)氣(qi)(qi)溫(wen)(wen)(wen)在1.9℃~4.4℃之間?極端高(gao)溫(wen)(wen)(wen)36.6℃,極端低(di)溫(wen)(wen)(wen)-45℃。年(nian)(nian)≥10℃積溫(wen)(wen)(wen)為(wei)1900℃~2800℃,并(bing)呈由南至(zhi)北(bei)(bei)增加趨勢?年(nian)(nian)日照(zhao)時(shi)數(shu)2350~2450小時(shi)?年(nian)(nian)降水量(liang)由南向(xiang)北(bei)(bei)略有減少,為(wei)834~673毫米之間。無霜期大致為(wei)110~130天。一月(yue)平均(jun)氣(qi)(qi)溫(wen)(wen)(wen)約為(wei)-18℃,七月(yue)平均(jun)氣(qi)(qi)溫(wen)(wen)(wen)約為(wei)20℃左右(you)。該區夏(xia)(xia)季(ji)(ji)盛行(xing)(xing)西南風(feng)(feng),冬季(ji)(ji)盛行(xing)(xing)西北(bei)(bei)風(feng)(feng)。
保護區由于(yu)受到三個湖(hu)泊及森林等因(yin)素(su)影響,又具有湖(hu)泊氣(qi)候、谷地氣(qi)候和森林氣(qi)候的復合(he)特征。