In the paper, the stateofart and trend of the development of commercial space above the ancillary routes of Guangzhou Metro are presented. The principle and concept of the design of commercial space above the ancillary routes are studied in terms of function organization, passenger organization and firefighting design. The author believes that the design principle mentioned above can be summarized as “4 synchronization”, “independence” and “harmony”. The design concept mentioned above involves the ratio among all the functional spaces, the calculation of the width of the passenger ways and the firefighting measures. The paper can provide reference for the development of commercial space above ancillary routes of Metro works in the future. 