Aiming at the particularity of high vacuum and the applicability of the anti-IR smoke in outer space, the NIR attenuation performance of pyrotechnic anti-IR smoke was studied under different vacuums. Experiment results show that the smoke transmittance increases with the increasing of vacuum from 0.10 MPa to 0.04 MPa,and the increase amplitude between the near vacuum intervals is approximately equal. Analysis results show that the increasing vacuum,decreasing smoke mass concentration make the smoke NIR attenuation performance reduced.