Abstract: Polycarbonate power button of a factory broken in batches during use. The causes of fracture on polycarbonate power button were analyzed by means of macro and micro analysis, infrared analysis, gas chromatography-mass spectrometry (GC-MS) analysis and bending property test. The results show that the fracture power button occured brittle fracture. The reason for the fracture was that there was a small amount of acrylonitrile-butadiene-styrene copolymer (ABS) in the power button material, which reduced the bending strength of power button. Besides, the lubricant containing halogenated hydrocarbon seeped into the power button, which led to the further decrease of strength of power button, and finally led to low stress brittle fracture.