The testing of sun protection factor（SPF）for sunscreen product is important in order to provide correct information to consumers against the risks of skin diseases related to sun exposure. Both in-vivo and in-vitro methods used nowadays have their drawbacks. This study is intended to find another way to provide effective and accurate way for measuring sun protection factor（SPF）of sunscreen product. The results show that by improving the sample application method to give more uniform film can have more precise results of sun protection factor（SPF）. However, the substrate for application still need to be examined according to the formulation of the sunscreen products.