Abstract: Based on the interaction between atmosphere and radiance in the near infrared band, conducted is the remote sensing of low-level water vapor, a problem that is hard to solve through the infrared band. The reflectance in 940 nm channel, which is in a weak water vapor absorption spectral band, is calculated, and its sensitivities to various environmental parameters are analyzed. The results show that signals from channels in the 940 nm band carry water vapor information from the whole atmosphere. The water vapor amount can be probably retrieved from it.