In this paper two strong wind processes caused by cold air and depression are analyzed.It reveals that the rapidly growing of the surface pressure gradient because of the depression axis suddenly turning toward northwest is one of the important reason which occurs the strong wind along the coast of North Zhejiang Province.Meanwhile,the distribution features of the vertical descending velocity caused by the difference of divergence between the lower lever and the upple lever of two wind processes are pointed out.It indicates that the lower(not the middle) level momentum descending directly strengths the surface wind velocity.This may be the reason of different surface wind velocity of these two wind processes when the surface pressure gradient is nearly same.