Objective To evaluate the fit status of respirators and influencing factors of fit status through quantitative fitting testing. Methods Departments with different respiratory infectious disease exposure risks in 6 hospitals of different levels and properties were selected by stratified sampling, that is, hospital staff with low risk (ge-neral ward), medium risk (such as emergency and respiratory outpatient), and high risk (fever clinic, nucleic acid sampling point as well as department of infection control), including doctors, nurses, medical technicians and servicers, arch and folding respirators of two brands were tested, quantitative tightness and fitness of respirators were tested by environmental aerosol condensation nuclear counter method. Results A total of 320 staffs were selected from 6 hospitals to conduct the testing, before the formal fit testing, through professional guidance, the overall passing rate of the quantitative tightness check was significantly improved from 27.50% to 57.73% compared with the self-adjustment of the tested personnel. The passing rates of the fit testing of different respirators were significantly different (χ²=561.51, P < 0.001), with the lowest of 0.94% and the highest of 84.06%. After quantitative fit testing, when carrying out fit testing for standard movements, passing rates of arch A, folding A, arch B and folding B respirators were 50.00%, 58.25%, 66.67% and 85.67% respectively. Passing rates began to drop mainly after the left and right head swing. Conclusion Fit testing is a favorable tool to ensure the efficacy of respiratory protection, fit testing data should be fully utilized to provide suitable respirators for the staff.