A safety belt positioning device includes a top cover and a bottom cover pin jointed together, wherein a clasp is configured interior of a clasp-eye of the top cover, and the positioning device is fixedly secured directly on a location of the safety belt by means of the clasp, which not only effectuates easy installation, but also convenient adjustment thereof. The present invention is characterized in that the positioning device is moveably disposed on the safety belt, and upon using the safety belt, the clasp of the positioning device is utilized to fixedly secure length of the safety belt in accordance to physique of the passenger, thereby achieving objective of adjusting degree of tightness of the safety belt. Moreover, because of a tensile force of an interior spring, re-pullback on the safety belt will not occur, which thus provides even greater comfort to a passenger when seated.