Abstract: In order to realize long propagation length, a two-layer dielectric-loaded surface plasmon polaritions(TDL-SPPs) waveguide was proposed． The mode field distributions and propagation properties of the TDL-SPPs waveguide were studied by using finite element method(FEM). The waveguide sensitivity was also studied. The results show that the propagation length of the proposed TDL-SPPs waveguide is 2.4 times as much as that of the conventional dielectric-loaded surface plasmon polaritons(DL-SPPs) waveguide. The TDL-SPPs microring resonator based highly sensitive biosensor was demonstrated. The results show that the sensitivity is more than 411 nm/RIU and the detection limit is less than 1.210-5 RIU. The design and research on the biosensor based on TDL-SPP microring resonator is a valuable exploration in biosensing application with high sensitivity.