In order to obtain the optimized cutting quality of fracture splitting groove of 36MnVS4 connecting rod,fiber laser is used to study the laser processing technology of this fracture splitting groove.The effects of defocusing amount,laser peak power,pulse width,cutting speed and pulse frequency on geometric dimension were analyzed.The microstructure of the splitting groove was observed by laser scanning confocal microscope.By comparison,variation law of geometric dimension was obtained under different laser processing parameters.The results indicate that the negative defocusing amount is helpful for the fabrication of fracture splitting groove;laser peak power,pulse width,pulse frequency and cutting speed have great influence on depth and opening angle of the fracture splitting groove,but they have less effect on width and radius of curvature.At the same time,when the depth of crack groove is 0.5~0.6 mm,opening angle usually varies within 10°~25° small ranges.