On the basis of bilinear transmission rates βSI and SIS epidemic model in regardless of population dispersal, this paper designs a more practical SIS epidemic model by improving and adding influential condition caused by population dispersal. Meeting certain conditions with reality on the existence of equilibrium, by the basic productive number R0and eigenvalue theory this paper find that if R0＜1, the diseasefree equilibrium is local and asymptotically stable, while if R0＞1, the epidemic equilibrium is local and asymptotically stable. This model proposed enriches epidemic model types further.