A percussion and magazine revolving device of toy grenade launcher includes a magazine. The magazine forms annularly arranged cylindrical accommodation chambers receiving therein grenades and has a circumference along which holding pegs are arranged. A release plate is attached to the magazine and forms a pawl for selective engagement with the holding pegs. A trigger and a percussion mechanism coupled to the trigger are arranged on a carrier seat. The percussion mechanism has a top edge o which a drive bar is mounted. The magazine is rotated to compress an elastic element arranged therein. When the trigger is pulled, the percussion mechanism is caused to fire one grenade, and at the same time, the drive bar pushes the release plate away to make the pawl disengaging the holding pegs, thereby allowing the magazine to rotate an angle for being ready to fire the next grenade.