A door trim coupling device for a vehicle with improved assemblability and detachability may include a wire provided in a closed loop form, a locking device disposed in a door trim of the vehicle, the locking device being provided to selectively wind or unwind the wire and a mounting device disposed at the door trim and configured to be engaged or disengaged from the door panel of the vehicle by winding or unwinding of the wire. The mounting device includes a guide lever including an insertion hole and a guide groove extending radially from the insertion hole and a guide block slidably coupled to the guide groove and configured to be engaged with or disengaged from the door panel along a sliding direction.