The invention relates to a vein viewing instrument and an imaging method of the vein viewing instrument. The vein viewing instrument comprises an image collection system, a central control system and a projector. The image collection system and the projector are respectively electrically connected with the central control system. According to the vein viewing instrument, based on the time division multiplexing principle, a near infrared source is arranged in the projector, and the projector has both the light source function and the projection function, so that the size of the vein viewing instrument is reduced; light homogenizing systems such as a color splitting prism are further arranged in the projector, so that illuminance uniformity of projected near infrared light is good, the projected near infrared light can not exceed a preset projection light range, the use rate is improved, disturbance of the environment caused by leaking light is reduced, and power consumption is reduced.