Two dimensional (2D) materials have demonstrated huge potential in wide applications ranging from nanodevices to energy storage. In this work, we propose a series of double-metal MXenes functionalized with various terminal atoms (MM'CT), including B, N, O, P and S, based on density-functional theory (DFT) calculation. We screen out a series of stable structures and study their magnetic and electronic properties. We find that the magnetism of MM'CT can be regulated according to different transition metals and terminal atoms. The magnetic moments of CrTiCT and CrVCT (T = N, O or S) are mainly contributed by chromium, while those of MoVCT (T = N, O or S) are originated from vanadium. We also find that these monolayers are metal with spontaneous conductivity, which is favorable for the electrocatalysis. The Gibbs free energies for the adsorption of hydrogen atoms on CrTiCS, CrVCS and MoTiCP are close to zero, indicating their high catalytic activity for hydrogen evolution reaction (HER). Our findings suggest that the functionalized double-metal MXenes are promising materials for magnetic nanodevices and electrocatalysts.