Using a quasi-one-dimensional election gas model, we investigate the plasma excitation of quasi-one-dimensional nanostructure systems. The Eigen-equation of plasma oscillation in the quasi-one-dimensional systems is deduced based on the linear-response and electromagnetic theory. Numerical calculation for the plasmon spectrum is presented. The results show that the excitation spectrum of the finite-scale systems is discrete and depending on the size of systems strongly. As the size of system increases, the number of plasmon increases, the excitation spectrum decreases, and the mutual spacing becomes denser. In addition, the excitation spectrum increases with the electron density of the systems increasing, which is qualitatively consistent with the conclusion of macroscopic systems.