Abstract: With exerted different nitrogen larix gmelinii forest humus layer in Great Khingan as the research object, the correlation relations between the quantity of microbial and enzyme activity was analyzed.The results showed that： by inputting NH4 CI, there were very significant positive correlation between the number of bacteria and the invertase activity, the number of actinomyces and urease activity; the number of fungi had significant positive correlation with the activity of urease. With KNO3 applying, there were very significant positive correlation between the quantity of bacteria and catalase activity, and the number of actinomyces and invertase activity. By inputting NH4NO3, the number of fungi showed significantly positive correlation with the quantity of actinomyces; the number of bacteria had significantly positive correlation with the urease activity; the quantity of actinomyces and fungi had very significant positive correlation between catalase activity and invertase activity, respectively.