98.6877%。 The LS-SVM model of the rice straw gasification tar removal process by the catalytic cracking was improved. Linear kernel function was chosen as the kernel function of the model. Moreover, the validation of the improved model was conducted. On this basis, an optimized calculation of the rice straw gasification tar removal process by the catalytic cracking was done. The results indicated that the improved model had better simulation effects and generalization ability, and when the catalytic cracking temperature reached 949.1356℃, the gas residence time was 0.9819s, the maximum of the tar catalytic cracking rate can be 98.6877%.