Abstract: An efficient characteristic mode analysis (CMA) method is proposed for the design and optimization of plasmonic nanoantennas. Based on electromagnetic computation technology, a generalized eigenvalue equation for characteristic mode analysis is established by using the integral equation method based on the Poggio-Miller-Chan-Harrington-Wu (PMCHW) formula in computational electromagnetics. The-matrix fast algorithm is introduced and combined with the implicit restart Arnoldi iterative method to improve the efficiency of CMA. The characteristic modes, modal significance and surface current distribution of nanoantennas are analyzed by the proposed method, and different nanoantenna structures are analyzed and optimized. Compared with the traditional CMA method, the proposed method exhibits high solution efficiency and low memory consumption, which provides an effective scheme for the design and optimization of plasmonic nanoantennas.