Abstract: The behavior of a twostage slot ted gyroTWT is selfconsistently simulated in this paper by a single wave nonlinear code .The effects of the length and position of the sever and the lengths of the first and the second sections on beamwave interaction are analysed and discussed in details.　The influence of the velocity spread of the electron beam on the efficiency, gain, and bandwidth of the beamwave interaction is also simulated and discussed in details in this paper.The electron beam employed encircles around the axis of the wave guide.