Itinerant ferromagnetic SrRuO3 with a Curie temperature TC 160.7 K was prepared by a conventional solid reaction method. Its zero-field-cooled (ZFC) magnetization and field-cooled (FC) magnetization were measured over a temperature interval from 5–180 K, in a sequence of applied fields up to coercivity. The major hysteresis loops were measured over a range of temperatures, which span the ordered phase. An empirical model was proposed to analyze the ZFC behaviors by means of coercivities at different temperatures. The calculated ZFC magnetization is consistent with the measured ZFC magnetization. Different ZFC magnetization behaviors were explained by using this model. The results indicate that the various ZFC behaviors originate from the comparison between the temperature dependence of FC magnetization and that of coercivity.