In order to obtain a high sensitivity,linearity and large dynamic measuring range, a physical model for a novel surface plasmon resonance sensor coupled by side polished fiber and triangular nano-rod array was proposed.By using Finite Element Method (FEM),the strong evanescent field escaped from the polished region of the fiber excites three kinds of plasmon resonances,which are Propagating Surface Plasmon Resonance (PSPR),Intrinsic Surface Plasmon Resonance (ISPR) of the triangular nano-rod,and the Inter-rod Surface Plasmon Resonance (IrSPR),and correspondingly results in three resonance valleys in the transmission spectra of the sensor.Both the ISPR and the IrSPR are of Localized Surface Plasmon Resonance (LSPR),and present a relatively low sensitivity while yields in a high linearity to the change of the environment refractive index.On the contrary,the propagating surface plasmon resonance shows a high sensitivity but a nonlinear dependence to the change of refractive index.In the optimized design with a height of 100 nm for the triangular gold nano-rod,a sensitivity up to 12 882 nm/RIU is achieved in the range of 1.38~1.42 RIU.The proposed sensing structure utilizing the strong evanescent field of side polished fiber,integrates the merit of high sensitivity from propagating surface plasmon resonance,and also the merits of high linearity and large dynamic measuring range from localized surface plasmon resonance.The novel design has important research significance and is believed to developed into an important practical sensing platform.