The invention discloses a method and a system for acquiring application performance data, and a device. The method comprises: indicating a user terminal to execute a performance data acquisition application based on a preset Service and a Runtime database, filtering performance data corresponding to a to-be-detected application from the performance data output by the executed application, and outputting the filtered performance data to a corresponding log; and acquiring the performance data updated by the log in a monitoring manner, and writing the acquired performance data in a specified file. Through the method, with the application as granularity, application performance data and performance data of user real-time operation can be safely and simply acquired, and the method provides convenience for performance data analysis on a server-side.