Abstract: In order to improve the safety of oil production, the explosion suppression effect of N₂ and CO₂ under the condition of high temperature and high pressure in the wellbore needs to be studied. At present, there are few studies on the effect of different volume fractions of N₂ and CO₂ on the explosion characteristics of a fixed ratio of combustible gas to oxygen under high temperature and high pressure conditions. At 40 °C, the initial pressure of 0.5, 1.0 and 2.0 MPa, the time for CH₄/C₂H₆/C₃H₈ mixture to reach the maximum explosion overpressure, the maximum explosion overpressure and the deflagration index K_G under different N₂ and CO₂ volume fractions were studied and analyzed. The effects of different initial pressures and two types of inert gases on the explosion characteristic parameters were investigated. The test results show that the inerting mechanisms of N₂ and CO₂ are the same under different initial pressures; the inerting effect of CO₂ is better than that of N₂ and has the optimal point. Before this point, the inerting effect of CO₂ is gradually stronger than that of N₂, and the chemical effect is dominant, after this point the chemical action reaches its maximum effect, so the inerting effect of CO₂ is still stronger than that of N₂, but the advantage is gradually reduced.