Based on the theory of laser induced fluorescence, an optical patternation testing system was built on the constant volume chamber bench. The spray fuel beam angle and impact point characteristics of PFI and GDI gasoline engine injectors were studied and the influences of spray recording duration, recording interval and nozzle number on test results were analyzed. The result indicates that the optical patternation is applicable to both PFI and GDI injectors with different number of nozzle holes. The test data of this method are similar to that of traditional patternation, but they have a higher resolution and are more intuitive.