This research is to develop a processing technique for fabricating the three-dimensional nonwoven fabric with the sound absorption capability and flame retardant capability. Furthermore, the physical properties and functionalities of the three-dimensional nonwoven fabric are adequately evaluated and tested. Several nonwoven fabrics are fabricated by two polyester fibers with different denier numbers and the low-melting-point fibers. Then, multiple nonwoven fabrics are used to make three-dimensional nonwoven fabrics through lapping, needle-punching process. After being reinforced by heating in the hot air circulation oven, the physical properties of three-dimensional nonwoven fabrics such as tensile strength, breathability, sound-absorption coefficients, limiting oxygen index (LOI), and thermal conductive coefficients are properly evaluated. Subsequently, the influence of fiber faintness on the performance of sound-absorption and thermal insulation of three-dimensional nonwoven fabrics is carefully examined through the obtained results.