The aim of the research is to identify the factors affecting the selection of express transport service among Thailand e-commerce business. The samples were people who worked in e-commerce business and had the experience on using the transport express service. The 129 samples were selected base on formulation and theory of Cohen (1977) and increased to 150 samples in order to prevent error in data collecting process with purposive sampling method. The research result at significance level of 0.05 showed that services and reputation affected the decision on choosing the transport express service while price and company’s identity did not affect the decision on choosing the transport express service in the aspect of Thailand e-commerce business.