A module upgrade method and a module to be upgraded in an unmanned aerial vehicle (UAV) system are disclosed in embodiments of the present invention. The method includes: acquiring an upgrade file of the module to be upgraded; upgrading the module to be upgraded according to the upgrade file; judging whether the module to be upgraded is successfully upgraded; and if no, reacquiring an upgrade file of the module to be upgraded, and upgrading the module to be upgraded according to the re-acquired upgrade file until finishing upgrading the module to be upgraded. In this way, the upgrade success rate of the module to be upgraded can be improved by multiple upgrades, and the upgrade method is simple, convenient, easy to implement and high in reliability.