The invention relates to the technical field of vehicle parameter detection, and particularly relates to a whole vehicle steering parameter testing method and a testing system. When a whole vehicle steering stiffness test is carried out, increments of torque and a rotation angle are calculated through a relationship curve, and the increment ratio of the torque to the rotation angle is the whole vehicle steering stiffness; when a whole vehicle steering clearance test is carried out, the relationship curve for a steering wheel rotation angle and a wheel rotation angle is acquired and outputted through a central processing unit, and the steering wheel rotation angle when the wheel rotation angle just leaves a 0 position is the whole vehicle steering clearance; and a whole vehicle steering system friction test is carried out, the friction of the whole vehicle steering system under different rotation angles is characterized through the relationship curve. According to the brand-new testing method and the testing system, the steering stiffness, the clearance and the friction in a whole vehicle state are tested, vehicle turning, lane changing and other intentions are realized when the torque is applied to the steering wheel to generate the rotation angle and the wheel generates the rotation angle, and the problems of no whole vehicle steering parameter testing method and no system in the prior art can be solved.