Abstract: In this paper, the correlation of the channels in 5mm absorption band for ground-based microwave remote sensing is discussed and various methods for inverting temperature are compared. Sequentially, choosing optimal channels, samples of Beijing in summer and winter during 1970-1975 are tested numerically with both Monte Carlo method and statistical method for obtaining temperature and water vapour profiles. The rms errors for inverting temperature profiles are less than 1.5 K below 600 mb and 1.6 K below 700 mb in summer and winter respectively. The mean relative errors for nverting water vapour profiles are within 20% in the lower troposphere.