To study the relationship between infective characters of Capillaria hepatica in Mongolian Gerbil (Meriones unguiculatus) and the density of rodents and raptors, this research selected 14 experimental areas in Abagaqi and Dongwuzhumuqinqi in Xilinguole League, Inner Mongolia during July 2004. We used the number of burrow method to efficiently investigate the density of M. unguiculatus. Standard killing trap method was adopted to capture rodent samples and we observed and counted the density of raptors within 3 km2 over the experimental area at the same time. Captured rodents were subsequently dissected to check the infection of parasites. The regression analysis was used to analyze the data. Altogether 1 058 rodents were captured, and raptors were observed for 69 times (Table 1). As a result we found that the relationship between infection rate and rodent density was extremely significant (P < 0.01, R2 = 0.926), and so did the relationship between infection rate and raptor density (P < 0.01, R2 = 0.853). The infection rate would increase with the rising of rodent density and raptor density. Moreover, there is a significant duplicate effect between rodent density and raptor density. The predation of raptors would shorten the diffusion period of C. hepatica and aggravate the hepatic capillariasis.