Alnus formosana + Hemarthria compressa (A+H), Alnus formosana + Lolium multiflorum Lam (A+L), and Alnus formosana + natural grass (A+N), the comparative analysis of SOC(SOC) content, vertical distribution and seasonal dynamics of the three kinds of forest modes and the response of which to the fertilization suggests that the content of the SOC of the three kinds of forest lands under different herb layer in the soil which has been fertilized and unfertilized respectively are: A+L >A+H >A+N. The results mainly caused by the differences among herb layers. The vertical distribution law of organic carbon is no difference among three kinds of modes that the content of organic carbon would be decreased with the depth of soil layers. However, the reduction rate of organic carbon content in soil layers in the depth 0~20cm is more obvious than in 20~40cm. Fertilization can increase the SOC content, and especially in the shallow surface. The seasonal dynamics of the three kinds of SOC modes are basically same: the SOC content will reach the minimum in autumn, and then it will be gradually increased until the maximum is reached in the next summer. The main characteristic is that the relatively higher content of SOC is presented in spring and summer, which on the contrary in autumn and winter. The seasonal dynamics of SOC is insignificantly influenced by fertilization. For the soil organic content, the A+L is better than the A+H.