Abstract: Objective To understand the degree of underreporting of notifiable communicable diseases in Yunnan province and provide evidence for the improvement of the quality of communicable disease network direct reporting. Methods The survey was conducted in 138 medical institutions selected by stratified samplings in Yunnan province. Results A total of 1315 cases of communicable diseases were analyzed. The overall underreporting rate was 9.81%, the underreporting rates of class A, B and C communicable diseases were 0%, 8.37% and 11.90%, respectively. The differences on the underreporting rate among medical institutions at different levels and among different departments in a medical institution were statistical significant. The underreporting rate was 0% in provincial medical institutions, 4.20% in municipal medical institutions, 4.66% in county medical institutions, 16.16% in township health centers, 53.63% in village clinics and 18.01% in private medical institutions, and the underreporting rate was 10.94% in outpatients departments, 6.81% in inpatient departments and 21.62% in laboratories. Conclusion The management of communicable diseases reporting should be strengthened in medical institutions at all levels, especially at township and village levels. The health authorities at all levels should conduct supervision and inspection on the communicable disease reporting in medical institutions regularly.