A lens module includes a barrel (40), a plurality of lenses (42), and a light guide plate (60). The barrel is covered at one end thereof with a transparent board (50). The lenses are received in the barrel. The light guide plate, which is received in the barrel and is located in the light path of the lenses, includes a transparent sheet plate (61) and a plurality of high-transmittance areas (62) defined therein. The high-transmittance areas have a higher transmittance than that of the sheet plate, and the profile and the density of the high-transmittance areas increase with the increase of a distance between a center of the light guide plate and a center of a respective high-transmittance area.