As the high speed bearings, hybrid journal bearings are usually used in high and super high speed grinding machine spindle system. Since the bearing operates under high speed conditions, the excessive temperature rise of bearing is a key factor to lower the accuracy of the spindle system and limit the bearings working speed, so restrict the bearing applications. In this paper, the model of hybrid journal bearing is established to analyze the heat mechanism. In addition, the temperature field distribution for the certain hybrid journal bearing at high speed is studied by ANSYS considering the heat transfer characters between fluid and solid. The experiment of temperature for hybrid journal bearing system in super high speed grinding machine is also performed. The thermal properties and the measure for controlling temperature rise of such bearings are analyzed.