Abstract: Aiming at the requirement of radar health management of condition-based maintenance(CBM),this paper analyzes the testability design requirements of frequency source in digital array radar, puts forward the built-in-test(BIT) design scheme of frequency source based on synthetic instrument, introduces specification requirements, design principle and key technology solutions of the RF test module for BIT of frequency source, and provides analysis results of testability modeling. Compared with the traditional scheme, this scheme can not only significantly improve the fault detection rate, but also meet the accurate test requirements of performance parameters for health management.