The good DC magnetic properties can be achieved for 1J50 soft magnetic alloy by applying high temperature hydrogen annealing. Annealing process parameters, e.g., atmosphere, soaking temperature, and time, are critical to soft magnetic properties. Qualitative results had been done for years. However a quantitative research among process parameters, microstructure, and magnetic properties can be more comprehensive and specific. In this study, a serial of experiments for 1J50 samples under the Chinese national standards. The influence of annealing temperature and socking time on DC magnetic properties and microstructure of the samples has been investigated on DC magnetic properties and microstructure of samples. The result shows that annealing process parameters have a nonlinear effect on the development of material microstructure and magnetic properties. Furthermore, the models among magnetic property, grain size, and process parameters have been built to quantitatively describe the interrelationship in between.