Owing to hardware advancements, a resurgence of interest has emerged in low field MRI systems recently. However, the intrinsic low signal to noise ratio (SNR) due to the low magnetic field strength has hindered the acquisition of high-resolution images on low field MRI systems. Here we propose a non-local robust PCA-based method to jointly denoise multi-contrast images acquired on a 0.5 T MRI system. In-vivo brain data are used to test the proposed method. The results show that the proposed method outperforms BM3D and BM4D denoising methods.