The B2C e-commerce is fast developed in China, but the logistic activities are relatively lagged behind. So many of the B2C ecommerce corporations choose to run the logistic service on their own. The advantages and disadvantages of carrying on self-built logistic service are discussed. The research is to illustrate the choice of B2C corporations to carry on logistics service in China and to show the reason why choosing tree topology logistic network could be cost saving.