The invention provides an auxiliary experiment device for measuring the radius of the curvature of a lens through a Newton ring. According to the device, eight LED monochromatic light sources with different wave lengths are adopted, light emitted by the light sources is coupled into a light guide fiber, and an outlet is provided with a beam expanding lens and frosted glass. A CCD camera is arranged in front of an eye lens of a reading microscope, the CCD camera is connected with a displayer through an interface, and the Newton ring can be directly displayed on the displayer. The LED monochromatic light sources with different wave lengths are turned on and used as incident light sources of an experiment, a Newton ring device is lightened after the light is reflected by a semi-reflective mirror, the Newton ring is displayed on the displayer through the CCD camera, and measurement can be conducted by using the reading microscope. According to the auxiliary experiment device, LEDs are used as the monochromatic light sources, the service life is long, preheating is not needed when experiments are conducted, lightness adjustment is convenient, eight monochromatic lights with different wave lengths can be obtained, the experiments are rich in content, student data are not prone to being similar, the Newton ring is directly displayed on the displayer through the CCD camera to be observed and measured, convenience is brought, and effort is saved.