Hill plot is a well-known criterion of the f-electron element interatomic threshold-distance separating the nonmagnetic state from the magnetic one in actinides or lanthanides. We have reinvestigated the Hill plot of Ce compounds using a commercial crystallographic database CRYSTMET, focusing on a relationship between the Ce-Ce distance and the magnetic ordering temperature, because a Ce compound with no other magnetic elements scarcely has a magnetic ordering temperature higher than 20 K. The Hill plot of approximately 730 compounds has revealed that a Ce compound, especially for ferromagnet, showing the high magnetic-ordering-temperature would require a short Ce-Ce distance with a suppression of valence instability of Ce ion. Through the study, we had interest in Ce2AuP3 with the Curie temperature of 31 K. The ferromagnetic nature has been examined by a doping effect, which suggests a possible increase of magnetic anisotropy energy.