Abstract: This paper discusses the computing formula for the anallactic telescope with negative focusing lens or positive focusing lens.It has been fourd that these formulas are identical,and the distance between the focusing lens and the reticul is not long enough for the compensator.The telescop objective system consisting of three lens clusters can solve the problem mentioned above.This paper presents the computing methods for the parameters in the system mentioned above,the programme and the example.This can facilitate the desing of the automatic level.