A reliable remote upgrade scheme is designed through the in application programming (IAP) of GD32. Under the condition of the existing communication interface, it is unnecessary to operate the BOOT signal of the microprocessor and connect the cable to upgrade the application program of GD32 microprocessor. Under the condition of ensuring the success and reliability of the upgrade, the scheme greatly saves the labor cost and time cost caused by dismantling the upgrade cable in the past, which has a great reference value for the remote online upgrade of multiple embedded-systems equipment.