Abstract: The phase-field method was adopted to investigate the effects of noise, initial crystal nuelei's radius, anisotropy and super-cooling degree on the simulation of dendritic growth in Al-Si alloys. The results show that if the initial crystal nucleus is not melted, its size has nothing to do with the simulation results. With the coefficient of interfaeial anisotropic strength increasing, the dendritic tip's growing speed increases linearly, while its radius decreases parabolically. The lower the sub-cooling degree is, the more difficult it is to find secondary dendrites. As a result, the influencing factors in phase-field simulation have important impact on dendritic growth simulation.