Zinc acetate serves as the catalyst in the synthesis reaction of VAc, the activity of zinc acetate will lose with the changes of the using time, temperature, space velocity, molar ratio. For the realization of soft measurement of the catalyst activity, the mathematical regression method and support vector machine (SVM) method are combined to model. By adopting the method of mathematical regression, the main change trend of catalyst activity can be illuminated with the change of response time; The support vector machine (SVM) method is used to amend the main trend to truly achieve the accurate and reliable soft measurement of catalyst activity[1]。The simulation is proceed by the MATLAB to compare to the field datas, the simulation results show that the model established by the mixed modeling approach is high-precision and reliable. The requirements of the soft measurement for catalyst activity in VAc synthesis can be satisfied.