A wavelength conversion module, a method of forming the same and a projection apparatus are provided. The wavelength conversion module includes a substrate and a wavelength conversion layer. The substrate has a rough surface including two first regions and a second region located between the two first regions in a radial direction on the substrate. The wavelength conversion layer is located on the substrate and includes a wavelength conversion material, a bonding material and diffuse reflection particles. The wavelength conversion material is distributed in the bonding material. The diffuse reflection particles are located on the rough surface of the substrate and between the wavelength conversion material and the substrate. A second density of the diffuse reflection particles in the second region is greater than a first density of the same in one of the two first regions.