Abstract: A method for calculating accessibility with open source data from internet maps is put forward. Based on the open source map database from internet providers, path finding algorithm ports provided by internet maps such as walking and cycling are called upon and are associated with the time cost and public facilities concerned in the planning research, so that index related to accessibility can be quantitatively evaluated with precision. This calculation method eliminates data collection,processing and modeling in conventional accessibility calculation,which greatly reduces workload and has the advantages of high consistency with real life scenes, simple and efficient operation, and strong applicability. Taking Shenzhen Metro as an example,the fixed cost accessibility and public service accessibility of Shenzhen rail transit stations are calculated and analyzed,through which the simplicity of the method is verified.