In Heihe area of Heilongjiang, site factors and stand factors in monitored sample plots of Malacosoma neustria testacea Motschulsky were investigated from 2011 to 2013, the effects of these factors and the biodiversity index on average population density of Malacosoma neustria testacea Motschulsky were analyzed. One-way analysis of variance(ANOVA) and Tukey tests showed that average population of Malacosoma neustria testacea Motschulsky in shady aspect was significantly higher than that in the sunny aspect, semi-sunny aspect and semi-shady aspect; average population of Malacosoma neustria testacea Motschulsky with elevation 301?400 m was significantly higher than that with elevation 401?500 m and 501 m above; average population of Malacosoma neustria testacea Motschulsky with canopy density of 0.5 was significantly higher than that of 0.4, 0.6 and 0.7, with canopy density of 0.6 was significantly higher than that of 0.4; average population of Malacosoma neustria testacea Motschulsky with the proportion of Quercus mongolica Fisch. ex Ledeb. above 60% was significantly higher than that with 0?29% and 30%?59%. Slope position and gradient showed no significant influence on average population density of Malacosoma neustria testacea Motschulsky. The average population density of Malacosoma neustria testacea Motschulsky was the highest under middle gradient, shady slope, steep hill, elevation 301?400 m, canopy density 0.5 and proportion of Quercus mongolica Fisch. ex Ledeb. >60%. The average population density of Malacosoma neustria testacea Motschulsky was the smallest under upper high slope, semi-shady slope, flat gradient, elevation >501 m, canopy density 0.4, and proportion of Quercus mongolica Fisch. ex Ledeb. 30%?59%. The results of correlation indicated that slope position, aspect, canopy density, Simpson index and Shannon-Wiener index demonstrated positive impact on the average population density of Malacosoma neustria testacea Motschulsky, while gradient, elevation and the proportion of Quercus mongolica Fisch. ex Ledeb. demonstrated negative impact.