Abstract: The article analyzes the respiratory resistance generation mechanism and influence factors of positive pressure oxygen respirators and verifies the correctness of theory analysis by experiments. The results show that respiratory resistance includes periodic dynamic pressure loaded in airbag and flow resistance in pipe sturcture; the main factors of air flow resistance in decreasing order are pipe diameter or equivalent diameter, gas flow (respiratory flow) and pressure; the periodic dynamic pressure loaded in airbag is determined by spring force and the cross-sectional area of platen.