Background：Special relativity treats a moving object as a rigid body and does not discuss the relativistic effects of the motion of the particles that make up the object. This unrealistic approach has misleading effects on the "application of special relativity" and the "concept of space-time". It is necessary to eliminate this misleading effect. Methods：Considering the actual composition of moving objects, the effect of motion on mass is obtained according to the relativistic mass velocity relation, and then the actual relativistic motion effect is obtained. Results：The volume of a non rigid body shrinks in all directions due to motion. This is inconsistent with the conclusion that the moving space contracts only in the direction of motion. When a non rigid body moves at a super high speed, the space around it will be distorted (even if the object is only inertial, the space is not guaranteed to be flat). Conclusions：The actual composition and structure of a moving object cannot be ignored. The motion of space and the contraction of space due to motion are unrealistic. This leads to the doubt of the world view that "space has relativity".