Abstract: In this paper,the temperature distribution of crystal,the temperature and velocity distributions of melt are calculated numerically for GaAs crystal growth with emphasis on the whole growth process from seeding,shoulder,fixed diameter to derminator growth,and the factors which influence the fluid flow and heat transfer such as rotating direction and rotating rate of crystal and crucible etc.are analyzed. Experimental results are given to compare with the calculating results. and it is found that two of them are agreement.