Abstract: The code bias in the receiver instrument deviation is an important factor affecting the accuracy of the total electron content in the ionosphere. If the effect of the code bias of the instrument on the ionosphere is ignored, the 9～30 TECU deviation can be brought to the solution of the electron content, so the exact solution of the machine code deviation is crucial. This paper uses 6-day GPS dual-frequency observation data and joints spherical harmonic model to estimate the differential code bias in the receiver on the basis of least squares. The results are compared and analyzed with the solution given by the CODE analysis center ionosphere product,at the same time,this paper also evaluats the accuracy of receiver differential code bias estimation. The results show that the results obtained by the estimation method in the paper are basically consistent with the results given by the ionosphere products in the CODE analysis center, and the estimated accuracy is quite high, therefore, this method has certain validity for the extraction of differential code bias.