Abstract: A new viewpoint was put forward for the magnetic heat treatment theory of low carbon steel.It was considered that heat preservation with high temperature for a long time in the austenite region has little effect on the magnetic properties of low carbon steel, and the phase transformation process in the two-phase region was the key.According to the new point of view, a new process was put forword, and the correctness of the viewpoint was confirmed by the experiments. The results show that the new process time is only 1/2 of the original process time, while the magnetic properties remain basically the same level as the original process.