Abstract: [Objective] The aim of this study was to evaluate the control effect of 20% iodine oligosaccharide acids on rice blast (Magnaporthe oryzae), to develop novel agents for control of rice blast. [Method] This study was tested by field trials, with 75% tricyclazole WP and 40% isoprothiolane EC as the control medicament. [Result] The results of the field control effect showed that 75% tricyclazole WP diluted 2500 times > 20% iodine oligosaccharide acids diluted 1000 times > 20% iodine oligosaccharide acids diluted 1500 times > 40% Isoprothiolane EC diluted 1000 times > 20% iodine oligosaccharide acids diluted 2000 times > 20% iodine oligosaccharide acids diluted 3000 times, which field control effect was 97.32%, 95.48%, 93.51%, 87.32% and 79.57%, respectively. The control effect of 20% iodine oligosaccharide diluted 1000 times was equal to 75% tricyclazole WP diluted 2500 times and 20% iodine oligosaccharide diluted 1500 times was equal to 40% isoprothiolane EC diluted 1000 times at P=0.05. Moreover, the rice which sprayed 20% iodine oligosaccharide acids growed better than sprayed the control medicament and water. [Conclusion] 20% iodine oligosaccharide acids has good control effect on rice blast and had the potential to develop agents for control rice blast.