Abstract: Based on the general difference of the strain values at the same measuring points between solid rocket motor static firing test at room temperature and hydrostatic test, the influence of modulus, size and shapes of grain on the pressure-sinkage characteristics of the carbon fiber composite winding structure layer was studied in this paper. According to the test results of the composite case under different grain conditions, the main reasons for the difference of the strain distribution on the surface of the case under different grain conditions were investigated based on the progressive damage numerical calculation and analysis. On this basis, the elastic layer-pressure bearing structure layer analytical model was established for the pressure-bearing characteristic section of the cylinder section of the case to analyze the characteristics of grain-composite winding structure layer characteristics, and the stress analytical solution of the pressure-bearing structure layer was calculated. Combined with the numerical calculation analysis based on parametric modeling, the effects of mechanical properties, size parameters and different structural forms including star grain and wagon wheel grain on the pressure-bearing characteristics of the composite winding structure layer were compared and analyzed. The results show that the different structure forms of the grain hardly cause the variation of the stress distribution on the surface of the composite winding structure layer, but have a great influence on the stress values of each position of the composite layer. The basic performance is that with the grain burning, the load shared by the grain decreases, the principal stress of the structure layer increases, and the strain response value of the case increases. Combining the analytical solution calculation results with the numerical calculation results of parametric modeling, it can be seen that when the modulus of the grain is smaller, the influences of the change of the grain thickness on the stress response of the winding layer decreases. Similarly, the smaller the thickness of the grain is, the smaller the influence of the modulus change on the stress response of the winding layer is. Compared to the case without grain, when the thickness of the grain is 20% of the nominal value of the case radius, the variation range of stress response deviation of winding layer is only 1%~1.54% when the modulus of charge column changes from 5 MPa to 25 MPa. The characteristic length of star grain and wagon wheel grain is the dominant factor affecting the stress response of the winding structure layer. The stress variation of the winding layer caused by the change of the number of star angles or spokes is less than 1%.