The misalignment of the rotationally symmetrical electron optical system caused by manufacturing and assembling tolerance is an important limitation factor for further improving the image quality. The finite-difference method is first used to calculate the three-dimension field to analyze the problem of the misaligned electron lense. The influence of the misalignment of equi-diameter cylinder bipotential immersion electron lense on image quality are given. Experimental tubes are also manufactured. It is shown that the theoretical computations are in good agreement with experimental values.