The purpose of this research is to lead the design guidance to obtain the best internal structure in a small-sized wind power generator that can rotate at a low wind velocity. Some experiments have been conducted in the past, and it was found that the analytical results coincide with the experimental ones In the present report, two analysis were conducted One is to confirm which material in the core is suitable. The other is to understand how the number of coil and magnet effect on the efficiency of the generator. The objective generation of designed generator was set as 5 kilowatt.