The invention discloses a processing method of a thermal compensation molybdenum wafer surface coating for manufacturing a high-power thyristor, and belongs to a high melting metal deposition processing method of pure molybdenum material surface. Rhodium or ruthenium with purity of more than 99 percent is used as a target; a thin layer of the rhodium or the ruthenium is deposited on a molybdenum wafer by a double-layer glow plasma diffusion metalizing technology; the adopted process conditions are as follows: the workpiece voltage is more than 600V and less than 900V, the source voltage is 850V to 1,000V and the workpiece temperature is more than 900 DEG C and less than 1,200 DEG C; and the treatment time is 0.5 to 2 hours. Compared with the conventional methods of plating and electron beam assisted physical vapor deposition and the like, the production flow is short, and the yield and the coating bonding force are high. The method particularly can be applied to processing of surface deposited rhodium or ruthenium coatings of thermal compensation molybdenum wafers of ultrahigh-power high-power thyristors in the fields of ultra (super) high voltage direct-current power transmission engineering, high power grid networking, high-speed locomotive traction and the like.