Different materials, different sizes of load plate grain mass flow sensor and different ranges of grain mass flow sensor elastic component were designed. Experiments were finished in the grain mass flow load simulation test device. The experiment results showed that parameters were closely related with precision. On the basis of this test, the grain flow effect on the measurement accuracy was researched. The experiment results showed the error of this load plate grain mass flow sensor was within 2% during the grain flow rate was 0~2kg/s. When the grain flow rate was more than 2.5kg/s, the error exceeded 5%.