On the basis of the aftershock frequency estimation method，the coseismic static coulomb stress changes calculation and rate- and state-dependent fault constitutive law， we calculate the Wenchuan “direct”aftershocks frequency and the coseismic static coulomb stress changes of its aftershock zone in the different areas nearby． We find that the forecast result is lower than the actual significantly in the main fracture zone，especially in the south of the fracture，because of the decrease of the calculated coseismic coulomb stress change． It also shows that the effect time of the coulomb stress changes on aftershock activity is associated with the lower magnitude，which is about 15 ～ 16 months for the aftershocks above ML4. 0，and close to 60 months for that above ML3. 5． In this period，the ratio of the “direct”aftershocks caused by coseismic coulomb stress changes lies between 44. 7% to 48. 6% ，which suggests that，even in the“effective”period of coseismic coulomb stress changes，there is about half of the aftershocks independent of the coseismic coulomb stress changes in the fracture zone of the mainshock． It is pointed out that those aftershocks may be related to the afterslip or the viscoelastic relaxation process，which are time dependent cases．