Abstract: In order to reveal the relationship between the cutting temperature in machining carbon fiber reinforced plastic (CFRP) and the cutting factors, orthogonally free machining tests on CFRP unidirectional laminates were conducted. The cutting temperature was measured using OMEGA-0.05 mm K type high sensitive thermocouple. Discussions were made about the effects of cutting parameters, geometric parameters of tools and material parameters on cutting temperature. The results show that cutting speed, cutting thickness, relief angle of tool and blunt radius, in the sequence of descending, have great influence on cutting temperature. The influence of cutting parameters on the temperature is not affected by the fiber orientation angle. Unlike metal materials, the cutting temperature is greatly influenced by CFRP fiber orientation angle. The cutting temperature cut along fiber orientation is significantly higher than that opposite fiber orientation. The maximum cutting temperature is present to the fiber orientation angle of 90°, and the cutting temperature at the fiber orientation angle of 90° is 2 times of that at the fiber orientation angle of 0°. The spring back of CFRP has great influence on the contact condition between the tool flank and the machined surface, which will affect the cutting temperature eventually. This has exacerbated the anisotropy of the cutting temperature. Moreover, the heat in the third deformation zone has prominent effect on cutting temperature. CFRP has a narrow cutting temperature range, maximum cutting temperature is about 300 ℃, which will make cutting quality more sensitive to temperature changes.