A method for label-free imaging to single nanoparticle by evanescent wave in-plane scattering is presented. Using the two evanescent waves of total internal reflection (TIR) evanescent wave and surface plasmon polaritons (SPPs) to interact with a single nanoparticle, respectively, which excites the nanoparticle polarization and scatter. Generated interfacial scattering is interfered with incident evanescent wave, which forms a characteristic imaging of the polarization field of the nanoparticles and the parabolic interference fringes. Single nanoparticle label-free imaging is performed on three polystyrene nanoparticles with the diameters of 500, 200, 100 nm. The imaging results of two evanescent wave in-plane scattering on single nanoparticle are compared. It indicates that the nanoparticle polarization of SPPs in-plane scattering is approximately 10 times stronger than that of TIR in-plane scattering and close to dark field imaging. As a result, SPPs in-plane scattering manifests the better sensitivity to label-free single nanoparticle imaging. This single nanoparticle label-free imaging method can be extended to areas such as virus detection and single bio-molecule imaging.