Mechanical stirring and mixing is one of the essential operation in the fields of food processing, construction, pharmaceuticals, metallurgy, paper making, etc. It has great economic value and application prospects. The mixing uniformity is an important index to measure the quality of mechanical mixing. The study of its mixing uniformity measurement and characterization is still one of the research hot spots in this field. In order to accurately measure the three-dimensional spatial multiphase mixing effect under mechanical stirring drive in real-time, a three-dimensional mixing effect accurate measurement method was proposed, and the overall average mass metric Q was calculated to characterize the mixing effect by analogy with the concept of potential energy, in order to overcome the one-sidedness of the pseudo-uniformity measure of the overlapping two-dimensional point set of particles. The accurate measurement method of three-dimensional spatial mixing effect was experimentally verified, and the overall average mass metric Q was calculated to characterize the uniformity of particle distribution. The relationship between the motor speed and the mean relative motion velocity of red spheres was analyzed, and the results showed that different rotational speeds and frequency conversions had significant effects on the relative motion velocity variation of tracer particles. In particular, the two-dimensional and three-dimensional mixing uniformity were compared in this work, and the two-dimensional mixing homogeneity measurement method was obviously not accurate enough, there was a large deviation, 75% higher than the average deviation of three-dimensional, three-dimensional spatial mixing homogeneity measurement method calculation results had better reflection of the real mixing effect. The two commonly used methods of mixing uniformity measurement, CD and WD, were compared with method of this work, and the characterization of mixing uniformity by CD and WD methods both failed. The feasibility as well as the accuracy of the method in this work was further verified.