The part of Wandashan Mountains, located in Heilongjiang province, was the area that the density of wapiti was very high. In recent years, the amount of wapiti declined extremely because of many reasons, such as human activity and illegal hunting. For taking conservation measures scientifically and efficiently, we probed into population size and sex ratio, and analyzed its living conditions in this region by molecular method. This method is a good way exactly to obtain the population demography and much information of population genetics, and is widely adopted by great many researchers. We collected 210 fecal samples of wapiti in Wupao forestry farm of Wandashan Mountains in two winter seasons, in 2006 and 2007, by tracking fresh foot chains. Finally, we successfully isolated 167 total DNA from them. We used 7 microsatellite loci that published in other's papers, with high polymorphic characters, to identify the genotypes of these fecal DNA by capillary electrophoresis. The identification result showed that these 167 fecal DNA belong to 66 individuals respectively. Using noninvasive capture-mark-recapture method, the population quantity was estimated. The theory of noninvasive capture-mark-recapture method is same as common capture-mark-recapture method that is generally used in ecology. The difference between two methods is that common capture-mark-recapture method needs to capture animal individuals, and the latter don't need to do that. Instead of capturing animal individuals, researchers only need to collect fecal pellets along animal's foot chains. The advantage of common capture-mark-recapture method is that wild animals need not to be killed or injured anymore. Based on noninvasive capture-mark-recapture method and the genotype data from 66 individuals, the average quantity and density of wild wapiti, promenading in the forestry farm, were estimated at 47 individuals (ranged 39-60) and 0.302 individual per square kilometer (ranged 0.251-0.386). Comparing our result with the consequence that was obtained by large sample-size method in 2002, the population size and density of wapiti in our studying area rise a little bit. Generally, SRY gene located in Y chromosome is used to identify animal sex. So, we used this gene to identify wapiti sex also. Then, combining two results from sex identification and individual identification respectively, we estimate sex ratio of this population at 1.00∶2.00 (female 22, male 44). Our result showed that there are too many male individuals in the region. This result is not consistent with the one in 2002. We considered that illegal hunting was the main reason to result in unbalanced sex ratio. Our results show that the wapiti population distributed in the forestry part of Wandashan Mountains declined directly these years. We still think that unbalanced sex ratio could produce a small effective population. In this case, more time would be needed to resume the local wapiti population. And it must be a hard work to get original population level. The wildlife conservation will become more and more important. Simultaneously, it is necessary to establish nature reserve in that region. We realize that wapiti population must be resumed and keep increasing if the conservation measures mentioned above could be taken.