Color-Filter-Free wavelength division multiplexing (WDM) Multiple-input and multiple-output (MIMO) Red-Green-Blue (RGB)-light emitting diode (LED) visible light communication (VLC) system using mobile-phone camera is proposed and demonstrated. Neither color filter nor chromatic color information is required in the proposed receiver (Rx). All image signal processing is based on the grayscale image, which can greatly simplify the WDM MIMO RGB-LED VLC system and save the cost of color splitting process. A proof-of-concept experiment is conducted. Optimized Scale-invariant feature transform (SIFT) algorithm is used to achieve the design.