Abstract: By using an f-plane barotropic quasigeostrophic model with the grid space being 5 km, twenty one experiments whose integration times are 36 h are performed in order to investigate the interactions between a typhoon vortex with the radius of maximum tangential wind equal to 100 km and adjacent mesoscale vortices which are located in the outer region initally. The distance between two centers of typhoon and mesoscale vortex is 200 km. Results show that whether the interaction can result in the typhoon intensification depends on two kinds of factors, one of them is the condition of the typhoon circulation, which contains the velocity maximum and the shearing of circular basic current, the other is the self condition of the mesoscale vortices, which contains the distribution, horizontal scale, intensity, and structure of the vortices.