Abstract: According to generalized Hooke's law,considering the deformation of silo wall,a formula for the side wall pressure related to the elastic modulus and Poisson's ratio of the silo wall material was derived based on some force analysis on stress element and then got.Compared with the Janssen formula,the calculated value of this paper was smaller than that of Janssen formula in the simulated test,and the error reached 8.7% when the grain depth was 1m.The result confirmed that the wall elasticity was also one of the factors that affected the calculation of the side wall pressure.As for the method of deducing the side wall pressure by using circumferential stress,its calculated value was larger than the calculated value of Janssen formula.It showed that the calculation result obtained by treating the flexible silo as a plane problem along the depth direction was larger than the actual value.