The invention discloses a pneumatic weft tension compensator which comprises a baseplate. Two ceramic ring grooves are formed on the front of the baseplate symmetrically according to a central line, a ceramic ring is mounted in each ceramic ring groove, an air incoming hole is formed in the lower portion of the baseplate and communicated with an air incoming pipeline inside the baseplate, an adjusting screw is arranged at the top end of the baseplate, a spring is sleeved on the adjusting screw, a left side face and a right side face of the baseplate are fixed on a left yarn penetrating plate and a right yarn penetrating plate through screws respectively, cushion blocks are further arranged between the yarn penetrating plates and the baseplate, and yarn penetrating holes are formed in the left yarn penetrating plate and the right yarn penetrating plate. By adopting the technical scheme, a stable conveying path is provided for fabric, weaving quality is greatly improved, stability in tension and capability of adjusting in the process of weft conveying are realized, and the pneumatic weft tension compensator is simple to operate, convenient to mount and low in cost.