Fractional density of states (FDOS) hinders the accurate measuring of the overall spontaneous emission (SE) control ability of a three-dimensional (3D) photonic crystal (PC) with the current widely used SE decay lifetime measurement systems. Based on analyzing the FDOS property of a 3D PC from theory and simulation, the excitation focal spot position averaged FDOS with a distribution broadening parameter was proposed to accurately reflect the overall SE control ability of the 3D PC. Experimental