The invention relates to a power transmission system of the automotive vehicle. A drive shaft structure, comprising a drive shaft and a hydraulic overload protector, the drive shaft comprises a first shaft and a coaxial second shaft, the hydraulic overload protector comprises a mounting rack, a crank shaft and at least a pair of hydraulic cylinders, a communicating tube is provided between two cylinders of the pair of hydraulic cylinders, a bi-directional pressure valve is provided on the communicating tube, said crank shaft comprises a spindle and a connecting rod shaft, said spindle is connected with said mounting rack rotatably, said first shaft is fixed with said mounting rack, said second shaft is fixed with said spindle, said connecting rod shaft is connected with said mounting rack via said cylinders. The invention discloses a drive shaft structure which can stop power transmission when the vehicle is overloaded, can restore power transmission automatically when the load meets the requirements and can buffer the resistance fluctuation during the driving process of the vehicle, the invention solves problems that he drive shaft will fracture when the vehicle is overloaded and when the resistance changes which increases the use cost and brings inconveniences to users.