Abstract: The method of mathematical equations ' simulation was used to prepare early indica rice flour with different protein contents( 0.5%,1.0%,3.0%,5.0% and 6.0%),and then the effect of protein content on gelatinization,the long- term retrogradation properties,microstructure,gel strength and crystallinity of early indica rice flour were investigated. The results showed that as the protein content was decreased,flour surface became smoother and microstructure of rice gel were tighter. The enthalpy value after long- term retrogradation was gradually reduced with the decrease of protein content,which indicated that low protein content could delay retrogradation.The indica rice gel strength also changed,when protein content was decreased,restoring force and chewiness force were increased,adhesiveness was decreased,and hardness was increased.The X- ray diffraction patterns of these six rice flours showed similarly a peak centered on 2θ = 15.17°,a doublet on 17.17° and 18.14°,and another single peak at 23.32°.And the crystallinity were 24.26%,21.79%,19.91%,21.45%,18.73% and 21.74%respectively.Consequently,protein content had little impact on the indica rice's crystallinity.All the results indicated that protein content interacted closely with related properties of indica rice.