An exemplary point light source (20) includes a light emitting body (230), and a light guide portion (210) adjacent the light emitting body. The light emitting body includes an illuminating portion configured for providing light beams, and a shell packaging the illuminating portion. The light guide portion is configured for guiding the light beams to propagate in desired directions. A size of a cross-section of the light guide portion far away from the light emitting body is less than a size of a cross-section of the light guide portion adjacent to the light emitting body. A backlight module (200) using the point light source is also provided.