NiAl/nano Al2O3 composite coatings are prepared on medium carbon steel substrate by electroless plating. The transverse-flow CO2 laser is employed to strengthen the coatings. The composition, microstructure and wear resistance of the coatings are characterized by energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffractometer (XRD), microhardness tester, friction and wear test (ball-on-disk). The effects of process parameters on microstructure and wear resistance of the coatings are investigated. Based on the high laser power, the fast traverse velocity and the large beam diameter, Ni0.77Al Fe0.23 intermetallics are synthesized in the coating. The microhardness of the coatings increases obviously due to the phase transformation hardening. The friction coefficient and wear loss obviously decrease after laser strengthening.