Major methods for determining a GPS receivers differential code bias(B), including the spherical harmonic function model and surface fitting model, have a high degree of computational complexity and poor efficiency. Based on the pseudorange data with carrier phase smoothing, global maps of vertical total electron content(V_TEC)of the ionosphere, and satellite B values provided by CODE, this paper proposes a new algorithm for determining the single GPS receivers B through interpolated V_TEC values from rotated maps and the pseudorange difference. The GPS receivers B values were estimated with the proposed method and observed data at IGS tracking stations, and were compared with those at the tracing stations provided by CODE. The results show that the new method can determine the GPS receivers B with an accuracy higher than 0. 4 ns.