The portable radar maintenance and test platform is an intelligent mobile technical support platform that integrates the functions of radar system performance parameter testing, fault diagnosis and maintenance protection, etc. The hardware system of the platform adopts the general test instrument based on the embedded chassis design architecture. The article for the general test instrument on board clock can not meet the radar system on the test instrument clock requirements. This paper proposes a highly stable clock source design suitable for the portable radar maintenance and test platform. Design solutions include the high stability thermostat crystal, FPGA, crystal power control module and power filter circuit module. The actual test results show that the high stability clock source design parameters achieve the output frequency stability of ±0.5×10^-6