The magnetic domain refinement was carried out by laser pulse scribing in order to reduce the core loss of SiFe. The laser pulses were generated by a Q-switched Nd:YAG laser, and the optical frequencies of the laser pulses were altered by using the SHG and the THG. The core losses were measured and analyzed to find optimal parameters of the laser treatment. The laser beam was focused with a spot size of 0.2 mm, and pulse energy of 10~30 mJ and the lines were scribed with a period of ~5 mm. The core loss was improved up to 19 % with the THG of Q-switched Nd:YAG laser in 3% SiFe.