Abstract: In order to address the mechanism of leakage rate variation for similar channel-type positive pressure standard leak holes under different operating conditions, a mathematical model was established by filling the channel-type leak holes with porous foam metal. Numerical simulations were conducted to analyze the impact of different operating conditions on the leakage rate of the channel-type positive pressure standard leak holes, and the velocity field distribution inside the foam metal was also provided. The results show that under constant air source pressure, compared with Air, He and D₂, H₂ has the largest leak rate, and the leak rate of the leak hole increases with the increase of air source pressure. Under the condition of constant pore diameter or porosity, the leakage rate of channel type positive pressure standard leak increases with the increase of pore diameter or porosity, and decreases with the increase of channel type positive pressure standard leak length. Nonlinear change of porosity can effectively improve and control the leakage rate. This study provides valuable reference significance for the production and development of positive pressure standard leaks, leak detection in metrology, and optimizing and designing sealing system performance by controlling leakage rates.