A musical instrument stand with a self-locking neck lock assembly for a guitar-shaped musical instrument has a post, multiple legs and a self-locking neck lock assembly. The self-locking neck lock assembly is attached to the post and has a stationary bracket, two locking palms, a movable bracket and a spring. The stationary bracket is attached securely to the post and has a U-shaped stationary collar having two distal ends. The locking palms are rotatably mounted on respectively the distal ends. The movable bracket is mounted pivotally on the stationary bracket and has a U-shaped movable collar. The movable collar has two distal ends mounted slidably to the palms to open or close the palms. The spring is mounted between the stationary and movable brackets and biases the movable collar upward to open the palms. When the movable bracket pivots down, the locking palms pivot to lock the neck.