Abstract: Based on the study of seed formation process,theoretical analysis was done for geothite growth.Then the effects of seed formation,air flow rate,stirring speed and drip feed rate of alkaline solution on the final form of geothite were investigated.It was found that crystal growth and secondary nucleation could occure in the same time and the operation condition must be choosen according to the reaction kinetics.The geothite form was affected by the form of seeds synthesized before,the particle size distribution got narrow,and dendrite and twin crystal decreased with increasing air flow rate and stirring speed,which modified the micromixing condition of the system. The coercivity and specific saturation magnetization of the magnetic powder which was made from the geothite synthesized by acidic method at optimum condition was 400 Oe and 72emu/g respectively.