In order to solve the problems of complex design, difficult development and poor maintainability of display system caused by the mixed programming of user interface and user application in artillery fire control system, the design of user interface and user application (UA) of display and control terminal is separated, and the design of UA is emphasized. The overall framework and complex interface of the fire control system are analyzed, the multi-DF file and multi-UA are analyzed and designed, and the UA design process is given. The test results show that the design can realize the dynamic interaction between UA and cockpit display system (CDS), and achieve the separation of user interface and user application of fire control system.