In order to obtain deflection device having wide bandwidth, small dispersion and high deflection sensitivity, a kind of traveling wave deflector is designed. Using commercial electromagnetic simulation software CST finite element method, bandwidth of traveling wave deflector in streak camera is studied, and the travelling wave deflector characteristics of dispersion curves, characteristic impedance changing with frequency and electron beam deflecting function are studied numerically using finite integration method. The comparison of deflecting sensitivity between traveling wave deflector and traditional plating deflector is made. Moreover, the electric field distribution in traveling wave deflector with sinewave scanning voltage signal is simulated. The results show that bandwidth of sharp top deflector is bigger than that of round top deflector and that bandwidth becomes smaller when legs of deflector become longer, with the biggest bandwidth of 7 GHz; phase velocity and group velocity decrease with the increasing of frequency; when frequency increases, a peak value exists for characteristic impedance; under the same dimensions, the deflecting sensitivity of travelling wave detector is two times higher than that of plating deflector; the electric field produced by sinewave scanning voltage appears periodic; the designed traveling wave deflector has wide bandwidth, of which dispersion is small in wide frequency range, and it can effectively make electron beam deflect.