A new chemiluminescent probe 10,10'-dimethyl-3,3'-disulfo-9,9'-biacridine DMDSBA) is used to label anti-CEA antibody, the molar incorporation is 1.15-1.32 mole of DMDSBA per mol anti-CEA; the conditions of labeling reaction, sandwich immunoassay and chemiluminescent reaction are studied. Moreover, a new double antibody sandwich chemiluminescence immunoassay is firstly established, the linear calibration ranges is 1.5-150.0 ng.mL-1 and the detection limit is 0.53 ng.mL-1. This method is used to detect cancer embryo antigen (CEA) in human serum, the results are well-matched with that of radio immunoassay.