The invention discloses a lens module light adjusting device, which comprises a working table and a light measuring box. A light source display box is arranged behind the working table; the working table is provided with a tooling plate for fixing a lens; two sides of the tooling plate are provided with light measuring controllers respectively; a locking rod is arranged on the light measuring controller at the left side; a lens adjusting rod is arranged on the light measuring controller at the right side; and the light measuring controllers are both connected with cylinders. As the tooling plate is arranged for fixing a lamp shell, the lens inside the lamp shell is tightened and adjusted via the locking rod and the lens adjusting rod on the light measuring controllers at two sides, the position of the lamp shell is sensed via a position sensor, the light adjusting precision is improved, the position of the lamp shell can be adjusted as a lifting mechanism and a sliding rail are arranged, and the light can enter the light measuring box conveniently. The structure is simple, the operation is convenient, and accurate light adjusting can be carried out on the lens.