A series of symmetric monomer of polyimide were prepared by condensation reaction and reduction reaction from p-chloronitrobenzene and the diols. The effects of the molar ratio of the materials, the amount of potassium carbonate, reaction time, reaction pressure and catalyst on the yield were studied. The optimum reaction conditions were obtained as follows: the molar ratio of raw materials1:2.5, the amount of potassium carbonate 15.9 g, reaction time 24 h；the reduction reaction pressure 0.6 MPa, the amount of catalyst 0.30 g, reaction temperature 70℃. The total yield of 1,2-bis (p-aminophenoxy) ethane was 74.1% under these condtions. The optimum reaction conditions were also applied in the synthesis of other 3 diamines with yields in the range of 49.4%~65.7%.