The invention relates to a pressurized rotary screw powder feeder. The feeder is composed of a speed adjustable motor, a powder chamber and a screw powder feeder body. The pressurized rotary screw powder feeder is capable of conveying a variety of powder such as coal powder, mineral powder, cement and lime; can automatically fill feed in a closed process and is good in environmental protection effects and easy to operate and control; can achieve pneumatic pressurized conveying at the pressure of 5.0MPa and above and is applicable to the section requiring pressure of a post-system; has a simple and reliable pneumatic mixing mechanism to effectively avoid powder bridging or wall hanging and to prevent powder clogging.