To solve the problem of the dynamic roll cap deviation when the high pressure grinding roll is working, a mathematical model to rectify the deviation is built according to the vibration principle and the principle of the hydraulic loading system controlling roll caps. Using the technical parameters of the GM1400×800 high pressure grinding roll, numerical calculations are carried out using Matlab software, and the effects of two-sided hydraulic loading system parameters on the roll cap deviations are studied. The results are verified by similar experiments that provide the theoretical foundation for the rectification of dynamic roll cap deviation. These results show that the maximum value of roll cap deviation decreases with fluid system resistance, and is no longer obvious after the two-side fluid system resistance reaches 6×107Ns/m5. They also show that the roll cap deviation stable value is mainly affected by the pressure difference and the accumulator working volume difference on both sides of the hydraulic system. The maximum value can thus be rectified to some extent by increasing the two-sided system pressure and decreasing the accumulator working volume appropriately. Increasing the non-driving side system pressure by 0.3 MPa or the driving side accumulator working volume by 0.002 5m3 can effectively rectify the deflection angle and roll cap deviation when the moving roller is stable. Similar experiments show that the numerical simulation results are consistent with the experimental change laws.