The invention belongs to the technical field of pipeline illuminating, and discloses a pipeline illuminating device and method. The pipeline illuminating device is provided with a waterproof pier base, and a lighting cover is fixedly mounted at the upper end of the waterproof pier base through a lighting cover fixing screw. A lighting cover sealing ring is mounted at the joint of the waterproof pier base and the lighting cover in a sleeving mode. A light guide pipe is fixedly mounted at the lower end of the waterproof pier base through a light guide pipe fixing screw in an inserted mode. A strip-shaped LED lamp is fixed to the inner surface of the lower end of the light guide pipe. The invention discloses an illuminating method at the same time. The pipeline illuminating device effectivelysolves the problem of the indoor illuminating brightness when the inclination of sunlight is large, and light can be more sufficiently collected and used for indoor illuminating. Diffusers are designed to be in a Fresnel lens array, and sunlight entering from different directions and different angles illuminates the indoor space evenly after passing through the diffusers. The waterproof pier baseachieves the effect of fixing the lighting cover and the light guide pipe, and achieves the sealing and waterproof effects at the same time.