In this paper, exponential total variational reconstruction model is introduced into computed tomography reconstruction model to establish an improved exponential total variational reconstruction model (METV) which can perform gray transformation at low energy to properly suppress the step effect and avoid over-smoothing at high energy. The existence of the solution of the minimization problem corresponding to the improved model is proved by variational method. It is also verified by experiments that under the condition of adding mixed noise of different intensity, compared with TV and ETV models, the reconstructed image of METV model can be very close to the real image, and the obtained image edge structure is clearer.