Graphene oxide (GO) was first synthesized by the improved Hummers W.S. method. It was then modified with manganese dioxide (MnO2) to obtain MnO2/GO composite material by chemical method.The parameters in the linear scanning adsorptive cathodic stripping voltammetry method (LS-AdCSV) include the amount of material, the accumulation potential and time, the potential sweep rate, and the influence of some organics and inorganics on the peak current of chloramphenicol (CAP) and tinidazole (TNZ), respectively. Under optimised conditions, the simultaneous determination of CAP and TNZ using the MnO2/ERGO/Naf/GCE sensor shows a linear concentration range from 1.0 to 20 µM, with detection limits of 1.50 M and 2.24 M. Furthermore, the proposed method was successfully applied for the simultaneous determination of CAP and TNZ in milk powder samples