Abstract: Using a cloud radiative parameterization scheme with different assumptions of ice crystal shape in the global climate model, changes in radiation and climate between the spherical ice crystal assumption and the multi-shape ice crystal assumption are discussed in detail. The results show that the influences caused by ice crystal shape assumption on ice cloud optical depth, radiative fluxes, atmospheric heating rate and temperature are obvious. Compared with the spherical ice crystal assumption, the global average ice cloud optical depth decreases by 0.28 (23%) and the decrease is most obvious in the tropical area with the absolute value up to 1.02. Little changes are found in land areas in the middle and high latitudes. Global average upward longwave radiation flux at the top of atmosphere increases by 5.52 W/m² (2.3%). Compared with observations, the multi-shape ice crystal assumption significantly reduces the underestimation by the spherical ice crystal assumption. The multi-shape ice crystal assumption weakens the shortwave radiation heating effect but enhances the longwave radiation cooling effect in the atmosphere, and these effects are particularly significant in the tropical upper troposphere. The change in the ice crystal shape has a significant effect on temperature, and temperature in the tropical upper troposphere decreases by more than 1.5 K. In summary, the change in ice crystal shape assumption has an important influence on the simulated radiation and temperature.