A new observation method of rainbow and neon phenomenon is proposed． By refitting the spectrometer with the light source and taking the self-made “optical lens and adding device”as the core，the dynamic adjustment of the light intensity of the light source，the length and width of the rainbow，the refractive index and other parameters is realized，which can stably present the curved rainbow phenomenon with adjustable curvature，and solve the difficulty in adjusting the parameters of the traditional device Neon presents the problem of single effect．The device is small and easy to carry，which provides a new enlightenment idea for guiding users to comprehensively learn the principle of neon imaging in multiple dimensions．