The functions of Flight Management System (FMS) of performance management and so on depend on repeated invocation and calculation of the onboard performance database.Thus the application of the onboard performance database has become the research focus of the aircraft manufacturers and system suppliers.To convert the raw aircraft performance data into onboard database, first-principle based method for FMS performance database design is proposed.The method establishes a basic performance model inside the FMS, and uses built-in aircraft model and algorithms to calculate performance parameters and fuel consumption.The contents of the airborne database, the table creation and format analysis, the software application and configuration management are studied, which supplies a reference for future onboard software development and airworthiness verification.