Solvent free coating method of coating resistance reducing coating steel pipe, which is characterized in that the inner wall including rust, wall spray and quality inspection in three steps, the specific steps are as follows: 1) surface treatment: on the inner surface of the steel tube derusted by shot peening machine, anchor depth of 30 ~ 50 m, clean degree reached 2 more than 2); group A: preheating coating epoxy resin coating the preheated to 50 to 60 DEG C, B was preheated to 30 to 40 DEG C; 3) pre mixed: determine the A components and B components of the volume ratio of 2.8:1; 4) spraying pressure setting gun model 104231921, spray into the air pressure 3.5 ~ 4.0kg/cm2; 5) with heat pipe: steel tube with heat, the temperature is not lower than 50 DEG C; 6) adjusting the pipe speed: steel speed is 19 ~ 22 rpm; 7) and adjust the speed of spray gun: gun speed is 8 ~ 10 m / min, the gun back speed Degree of 3 ~ 4 m / min; 8) quality inspection, according to the American Association of hydraulic C210 AWWA 2003 standard test and acceptance.