For the existence of different buyers and sellers, the paper explores the effects of platform charges on equilibrium price and price dispersion. The results show that searching cost is not the basic reason for price dispersion. The decrease range of searching activities in different buyers that result from platform charges is equal. In addition, all sellers will raise their prices when the platform charges them, but the increase range in two groups is not equal,  it leads to reducing price dispersion degree. When platform charges both sellers and buyers, sellers with the higher reputation will reduce the price of products and sellers with lower reputation will raise the price, and finally the price dispersion degree reduce or even disappear.