The invention provides a light module for treating alopecia. The light module includes a light source, a driving controller, a filter disc and a light shell. The light source is electrically connected with the driving controller through a hole in the top of the light shell; the light shell enables the light source to realize condensation, and an opening of the bottom is equipped with the filter disc; the filer disc is placed between the light source and an irradiation object, and consists of an orange optical filter, a lemon optical filter and an aubergine optical filter; and the steps are as follows: A) light filtered by the orange optical filter irradiates the head; B) light filtered by the lemon optical filter irradiates the head and the trunk; C) light filtered by the orange, lemon and aubergine optical filter combination irradiates all hair parts and the trunk; the intensity of light in the three steps is 5 to 50nW/cm2, and the time is 10 to 80min. The light module for treating alopecia has the beneficial effects that the light module is simple in mechanism, low in cost and easy to popularize, the method of application is easy to operate, and through a special color combination and irradiation sequence, a good effect of treating alopecia is achieved.