The invention provides a testing method for combined stress of an airplane brake system. The combined stress test section is incorporated into an extreme value environment condition in use to stimulate a using failure. According to the testing method for the combined stress of the airplane brake system, the overlaying effect is generated by simultaneously applying temperature and temperature changes, power supply voltage fluctuation, hydraulic stress and vibratory stress which exist simultaneously during using of the brake system, wherein the power supply voltage fluctuation is the power supply character, so that the failure stimulating effect is enhanced. A test for the brake system is completed under the combined stress condition within 90,000 min / 1,500 h, seven verifications such as the service life indicator for 2000 times of taking off and landing of the braking system, average failure interval time with 2000h of MTBF, high temperature, low temperature, vibrating, temperature impact and the power supply character are completed in one test, and the problem that the service life and reliability indicator of the brake system in the prior art cannot be comprehensively verified is solved. According to the combined stress testing method for the airplane brake system, testing cost is reduced, failures during using of civil airplane products are reduced, the flight attendance rate is improved, and reliability of a civil airplane is improved.