Abstract: For problem that a great deal of power loss of explosive-proof three-level converter with high power causes temperature rise and further affects converter performance, the paper analyzed principle, advantages and disadvantages of normal heat dissipation modes of electronic devices, and pointed out that the method using heat pipe combined with forced cold air is fit for heat dissipation of explosive-proof three-level converter with high power of coal mine underground. It also analyzed loss and temperature rise of main power devices of high power converter including IGBT, diode and fast-recovery diode under heat dissipation of heat pipe, and got formula of temperature rise of the power devices. The experimental result showed that error of calculated value according to the formula is in allowable range, which proves feasibility and correctness of the formula.