A fire control device for a toy gun and a method therefor are provided. The device includes a trigger switching module, a firing mode selecting module, a control module, a power module and a motor module. Through a selection via the firing mode selecting module, the control module can control the time that the power module supplies the motor module, so that the lasting time period that the motor module drives a firing module to fire can be controlled, thereby multiple firing modes, single fire, 3-round burst, continuous fire and weapon safety, can be achieved.