In this paper, we demonstrate a novel receiver in visible light communication system based on RGB LEDs. It contains three major parts the collimating lens, the spectro-device and the photodetector. The mixed RGB signal lights are captured, separated and received by the collimating lens the spectro-device and the photodetector respectively. Through the adjustment of the collimating lens, the receiver can receive enough light even if the distance between the signal light source and the receiver is changed. The receiver has the advantages of strong mobility and strong ability of receiving signal light. Based on the designed receiver the high-speed visible light communication system using RGB wavelength division multiplexing technology can have better performance.