A wavelength conversion module, a forming method of a wavelength conversion module, and a projection device are provided. The wavelength conversion module includes a substrate and a plurality of wavelength conversion units. The wavelength conversion units are located on the substrate, wherein the wavelength conversion units include a first wavelength conversion unit and a second wavelength conversion unit, the first wavelength conversion unit includes a first wavelength conversion material and a first doping material, the second wavelength conversion unit includes a second wavelength conversion material and a second doping material, the first wavelength conversion material and the second wavelength conversion material are different from each other, and the first doping material and the second doping material are different from each other. By the wavelength conversion units comprising different doping materials, low cost, good heat resistance and efficient light emitting are achieved.