According to the diffraction principle, a flattened shaping element is designed and prepared, which converts a Gaussian distribution of laser energy to a flat-top distribution. The laser dicing test of silicon wafers is carried out by using the 532 nm pulsed laser and the influences of laser energy, dicing speed and focusing position on the wafer cutting effect are investigated. The results show that based on the laser dicing by flattened beams, a groove with a width of about 16 μm and a depth of about 18 μm can be obtained, whose bottom is flat and wall is steep. In addition, the heat affected zone under the flattened beam is obviously smaller than that under the Gaussian beam.