Objective To compare the pass rate of fitness test for arch-shaped and fold-shaped medical protective masks, and explore the relationship between facial dimension and the fitness test of mask. Methods 320 health care workers from 6 hospitals in Beijing were selected. The facial dimensions were measured by right angle gauge, bending angle gauge, and leather ruler. Quantitative fitness test of a brand of arch-shaped and fold-shaped medical protective masks was conducted by TSI 8038/8048 mask fitness test instrument. Results The pass rates of fitness tests for arch-shaped and fold-shaped masks of 320 subjects were 44.38% and 84.06%, respectively, with statistically significant differences (χ²=103.765, P < 0.001). Analysis of influencing factors showed that morphological facial length had an impact on the fitness test result of masks. People with long morphological facial length fit better in arch-shaped masks, and people with short morphological facial length fit better in fold-shaped masks. Cluster analysis showed that arch-shaped masks fit large face better than small face, while fold-shaped masks fit small face better than large face. Conclusion There are difference in the fitness of arch-shaped and fold-shaped medical protective masks. The morphological facial length and the shape of the user's face are important factors influencing the fitness of masks. The results of this study can provide references to product design for mask manufacturers and guidance for health care workers in the selection of suitable masks.