Herein, the movement of hydrated cations in ionic-polymer metal composite (IPMC) is analyzed by the micromechanics method. Based on the mechanism of IPMC, the migration of hydrated cations is in a step-by-step order, and the aggregation of hydrated cations on the cathode side results in the bending of IPMC toward the anode. The physical models of the maximum displacement and maximum blocking force of IPMC are established, the Pt IPMCs are prepared by chemical deposition, and the calculated values are compared with the experimental values. The results indicate that there is water electrolysis in the actuation process of IPMC, which inhibits the migration of ions on the electrode surface and has a negative effect on the property of IPMC. By comparing the calculated value of the model with the experimental value, it is found that there is good consistency. The mathematical statistical metrics, mean absolute error, mean relative error, determination coefficient, correlation coefficient, mean square error, root mean square error, and relative root mean square error, are used to assess the model capability, which puts a theoretical foundation for the prediction and simulation of IPMC and promotes the further development and practical application of IPMC.