The invention discloses a vehicle transmission shaft detection tool and a mounting structure of a transmission shaft on a detection tool. The detection tool comprises a pedestal. Vertical supporting bodies are disposed on the two ends of the pedestal. Each supporting body is equipped with a vertical clamping groove, the two vertical clamping grooves face each other, and the two sidewalls of each clamping groove are provided with splines. A transmission shaft supporting block is disposed in each clamping groove, the two side surfaces of each transmission shaft supporting block are provided with splines that fit the splines on the two sidewalls of the corresponding clamping groove. Each transmission shaft supporting block is equipped with a central hole, and the wall of each central hole is provided with a central hole spline that correspondingly fits splines on the two ends of a transmission shaft. A calibrated scale for measuring the axial movement quantity of the transmission shaft is disposed on the pedestal in the length direction. The detection tool can detect many aspects of one product, such as the maximum operating angle of the transmission shaft, the length of a middle rod of the transmission shaft as well as the amount of sliding. Meanwhile, the detection tool exhibits good universality, and can be used for detecting transmission shafts with different models.