An improved mean backprojection algorithm based on an isopotential back projection algorithm of electrical impedance tomography (EIT) is presented by adopting the mean backprojection theory of computer tomography. The distance from the midpoint of an injected electrode pair to the midpoint of a measured electrode pair is taken as approximately the length of the projection routine which is introduced into the backprojection process. The positive and negative mean values of relative conductivities obtained by backprojection are computed. The final relative conductivities are the differences between the conductivity values obtained by backprojection and the corresponding sign mean value. If the results change sign, they are set to zero. Simulations and phantom experiments show that fewer artifacts are present in images reconstructed by mean backprojection algorithm than those reconstructed using the backprojection algorithm. The improved mean backprojection algorithm is more practical and effective than the backprojection algorithm.