This study focuses on the scenario of navigation and guidance for uses in large supermarkets. Have known the defects of GPS in indoor environment, Wi-Fi technology is chosen as the positioning technology. The purpose of this study is to analysis and evaluate whether a Wi-Fi positioning system can satisfy the user requirements based on different perspectives of it and how. Several parameters of a Wi-Fi based positioning system are analyzed in the following sections: positioning principle, accuracy, latency, cost, privacy. An overview of other existing other technologies is also presented in the end. The result from these parameters shows that a Wi-Fi based positioning system is an appropriate choice for this case.