Surface irradiation for refractory Ni-based alloy DZ4 was realized by high intensity pulsed ion beam (HIPIB) containing Cn+ (30 mol%) and H+ (70 mol%), with pulse duration of 70 ns and current density of 100 A/cm2, under the accelerating voltage of 250 kV; while the treating pulses were chosen as 5, 10 and 15 times. The surface microstructure changes before and after irradiation was analyzed by TEM. Results show that compared with the original sample, a polycrystal layer appeared on the topmost surface of the sample, no matter what times it was irradiated; the layer was composed of Ni, Cr, Al, Ti, W, Mo and Co elemental crystal with grain size of 5~10 nm. g ￠ phase did not exist below the polycrystal layer in certain depth, but its content increased gradually as the depth increasing.