Chemical vapor deposition (CVD) is one of the important methods for the synthesis of high quality MoS2 films at present. Herein, a facile model described the concentration distribution of MoO3 vapor is advocated for preparing MoS2 films with different morphology. Due to the gradual reduction in the concentration of MoO3 vapor from center to edge of the substrate surface calculated using this model, the morphology of as-grown MoS2 films changes from triangle to truncated triangle and then hexagon, respectively. The optimum concentration of MoO3 vapor for the growth of different morphology of MoS2 films is obtained by this model, and a direction for synthesis of MoS2 films with controllable morphology can been given. It is a simple way to control the morphology of objective thin films by tuning the concentration of precursor in CVD composition of 2D materials including MoS2 films.