This study is motivated by the fact that temperature control is very important for the success of laser assisted milling. A transient three-dimensional thermal model is developed using finite element analysis for laser assisted milling (LAMill) of silicon nitride ceramics, and then validated through a series of experiments of laser assisted face milling. This study aims to explore the thermal characteristics in LAMill of silicon nitride ceramics and thus provide guidelines on parameter selection for future operations. In addition, heat generation associated with machining is considered, and the effects of laser power, feed, and cutting speed on temperature are investigated. Simulation results show that heat generation associated with machining can be neglected. Laser power is one critical parameter for successful operation of LAMill. Moreover, both feed and cutting speed can affect the operating temperatures by varying feed rate; however, once feed rate is fixed, they have a little impact on the operating temperatures.