In order to meet the requirement of accurate detection for polarimetric microwave radiometer, in this paper, we study on the influence of attitude on brightness temperatures received by the radiometer. Correction for brightness temperatures errors is also analyzed. The relationship between the misspecification of the attitude and the incidence angle together with polarization rotation angle is established. The variation of brightness temperatures with the change of incidence angle and polarization rotation angle is simulated. We simulate the original observational brightness temperatures of the radiometer. A method based on the radiative transfer model for compensating attitude offset to correct brightness temperatures errors is presented. Taking vertical brightness temperature and the third Stokes parameter brightness temperature for example, our method can eliminate the influence of attitude offset on the observation of brightness temperatures effectively, the result can satisfy the accuracy requirement of data preprocessing for polarimetric microwave radiometer.