In mirrored aperture synthesis (MAS), the inverse problem is severely ill-posed, which can affect the accuracy of the solved cosine visibilities. Ultimately, errors in solved cosine visibilities degrade the quality of reconstructed brightness temperature images. In this paper, a brightness temperature reconstruction method based on Tikhonov regularization is presented to alleviate the ill-posed characteristics of the inverse problem. The simulations and experiments are carried out to demonstrate the effectiveness of the proposed method.