An epitaxy base including a substrate and a nucleating layer disposed on the substrate. The nucleating layer is an AlN layer with a single crystal structure. A diffraction pattern of the nucleating layer includes a plurality of dot patterns. Each of the dot patterns is substantially circular, and a ratio between lengths of any two diameters perpendicular to each other on each of the dot patterns ranges from approximately 0.9 to approximately 1.1. A semiconductor light emitting device, a manufacturing method of the epitaxy base, and a manufacturing method of the light emitting semiconductor device are further provided.