The lighting device contains a substrate and a plurality of lighting elements arranged in at least two parallel rows on a front side of the substrate. The lighting elements of the two rows neighbor on each other. The front side of the substrate is configured so that an included angle is formed between the lighting elements of the two rows. Their light therefore converges within a Quantum Dots (QD) tube before entering a light guide plate. A backlight module incorporating the lighting device as such not only provides high saturation and high chromaticity, but also achieves greater optical coupling efficiency, thinner light guide plate and QD tube, reduced material cost and dimension.