A laser is often considered to scribe the steel surfaces after cold-rolling and annealing to reduce the energy losses associated with hysteresis and eddy currents. In order to maximize the loss reduction of this process, the laser scribing technics was investigated in details. In this work, three laser scribing parameters including pulse energy, scanning velocity and scribing spacing, which are highly related to the loss reduction, were selected for the study. A L9(34) orthogonal experiment was designed and carried out by an Nd:Yag laser marking machine. The results indicate that the subsequence of significance of the three factors on core loss reduction is as follows: pulse energy, scribing spacing and scanning velocity. And an optimized combination of parameters is obtained by range method.