Synthesis systems composed of magnesium,aluminum,copper oxide,ferroferric oxide,calcium fluoride,tin oxide,tin and straw powders of rice,wheat,corn,rape or cotton were set at a fixed mass fraction,and chemical compositions of 227 groups of crop straw powders from different breeds or planting area were determined.Change rules of conversion rates,particle sizes and compositions of different nano-tin oxide products were analyzed and effects of the total contents of cellulose,hemicellulose and soluble sugar in crop straws on nano-tin oxide products can be obtained.Results show that all of these 5 crop straw powders are suitable for preparing nano-tin oxides via self propagating high temperature synthesis method and rice straw powder is the best one.The total contents of cellulose,hemicellulose and soluble sugar in straw powders of rice,wheat,corn,rape and cotton decline in turn,which leads to similar decrease of heat and gas production in synthesis systems containing of them,so that conversion rates and mass fractions of Sn of the nano-tin oxide products prepared from them fall in turn.However,there is no significant difference in mean diameters of nano-tin oxide products prepared from these 5 crop straw powders and no a common function relationship between total contents of cellulose,hemicellulose and soluble sugar in them and these mean diameters,which means it is impossible to adjust the particle sizes of nano-tin oxide products only by changing the kind of crop straw powders.