In this paper, the RKKY interaction formula of 2-dimensional magnetic alloy is derived by using the Green's function method. The result for large 2kfRji is in analogy to results of 1-dimensional and 3-dimensional magnetic alloy. Based on RKKY interaction formula, the RKKY Coupling resitivity of 2-dimensional magnetic alloy is calculated, it is divergent as T-1 at low temperatures. The T-1 divergencl can be removed by means of the ring approximation.