Method and apparatus for resource collision avoidance on sidelink are disclosed. One method of apparatus includes determining reserved resource on SL for a following SL transmission; transmitting information of the reserved resource to a mode 4 UE in a resource reservation field in SCI. Further, the reserved resource on SL is determined according to DCI received from a base station. Further, a resource guarantee indication, which indicates whether the reserved resource indicated in the resource reservation field in the SCI can be occupied by the mode 4 UE, is transmitted to the mode 4 UE.