The invention relates to a glass powder automatic adding apparatus of a steel pipe hot extruding bar coating table. The apparatus comprises a coating table and a rail dolly positioned right above the coating table. The rail dolly drives the bar to roll on the coating table. A powder adding hopper is arranged on the rear part of the rail dolly. A long-slot discharging port is arranged on the bottom of the powder adding hopper, wherein the length of the discharging port is no less than that of the bar. A mobile arc baffle is covered on the long-slot discharging port. The apparatus provided by the invention is advantaged in that: the powder adding hopper is directly arranged on the rail dolly which is used for driving the bar to roll on the coating table; and the movement of the rail dolly drives the powder adding hopper to distribute powder. Therefore, the apparatus is advantaged in simple structure and power saving. A switching drum is arranged in the powder adding hopper, such that powder discharging is more smooth and uniform. A horizontal powder scraping plate is also arranged, such that the powder on the coating table can be automatically leveled by scraping, and the powder layer thickness can be controlled. Therefore, uniform powder coating can be realized on surfaces of bars with different diameters. The operation of the entire apparatus is stable and reliable, and an automation degree is high. The working efficiency is effectively improved, the quality of the hot extruding steel pipes is improved, and labor intensity is reduced.