The invention discloses an online double-station mobile-type laser processing device for strengthening, toughening and repairing the surface of a steel rail by lasers. The online double-station mobile-type laser processing device particularly comprises a double-station mobile-type laser processing device, two sets of laser processing heads, two sets of laser beam motion actuating mechanisms, a control system and a laser guiding system. The mobile-type laser processing device of the invention has the advantages of small size and light weight, so the mobile-type laser processing device is suitable for manual transportation; by using the dedicated control system, the control is convenient; the operation can be conducted during the 'skylight' time for rail overhaul, particularly, the mobile-type laser processing device can simultaneously strengthen, toughen and repair various parts of the surfaces of linear steel rails, curved steel rails, guard rails, turnout junction and other double rails, more particularly, the rails are subjected to laser phase-change quenching, laser surface-melting quenching, laser cladding, laser alloying, laser texturing, laser shock processing and other treatment, thus greatly increasing the abrasion resistance of the strengthened steel rails. The online double-station mobile-type laser processing device has the characteristics of high processing efficiency, high portability, high processing accuracy and easy control.