Abstract: The authors made a survey among 1 , 565,538 children under 15 on claudication. The result showed that 603 patients with sequela were regarded polio paralysis. The sick rate was 36. 52/ 100 000. An analysis of the result showed that after the immunization of oral Polio vaccine,the pandemicity had been under control. Nevertheless ,the under -report rate was serious as 73. 4% of the patients could not tell when they had taken vaccine.