The weighted radiance of LED is one of the most important parameter in photobiological safety evaluation of LED, so a special measurement system was established which combined of a CCD camera simulated of the human eye imaging and a spectrometer. Reference the testing requirements in the standards, the deficiencies of the traditional luminance meter were analyzed theoretically and two typical LEDs were measured by the traditional luminance meter and the retina radiance meter. There were great differences between the weighted radiance in photobiological safety evaluation and the radiance in traditional optical measurements, and the special requirements made the traditional luminance meter cannot be able to measure the weighted radiance. Finally, the differences between the two luminance meters were introduced and test results were analyzed using the two luminance meters. The experimental results show that the weighted radiance of the white LED tested by the traditional luminance meter is 81.8 W/m2·sr, but the value is 137.0 W/m2·sr when the LED is tested by the novel system. Obviously, traditional luminance meter is not suitable for measuring the effective radiance and it will underestimate the hazard.