1. In a terminal device configured to process tasks, a method for processing a task in device management, the method comprising: receiving, from a device management server, a scheduler task, an execution condition for executing the scheduler task, and a processing rule for processing the scheduler task if the scheduler task has missed the execution condition because the terminal device adjusts a system time of the terminal device, wherein the processing rule includes executing the scheduler task or canceling the scheduler task; adjusting the system time of the terminal device by an adjustment time; determining that the scheduler task has missed the execution condition of the scheduler task during a jumping period caused by the adjustment time; and executing or canceling the scheduler task based on the processing rule.