Abstract: Based on a WGD-6 optical multichannel analyzer and a TS-100A fiber spectrometer, two kinds of experiment systems were designed to test the optical properties of 5 kinds of different colors LED (such as red, yellow, green, blue and violet), including the wavelength, the coherent length and the spectral linewidth of LED light source. The results show that the measured LED spectral power distribution approximates to Gaussian distribution and it is a typical narrow spectrum. The half-intensity width of 5 kinds LED is all less than or equal to 36.47 nm, so the LEDs spectral purity is good. The half-intensity width of green light LED is the largest and the violet light LEDs is minimum, so the mono=chromaticity of violet light is the best. The measurement results of the two methods show that they are in agreement and the test data is nominal with manufacturer.