Abstract: This paper elaborated the GPS observation data quality checking method, principle and main evaluation index, and introduced the TEQC and RTKLIB software in the data quality analysis function. By GPS data quality analysis and contrast to each other, We found that : 1) TEQC runs in DOS environment, with poor man-machine interaction, and RTKLIB software runs in Windows system, which is convenient to operate.2) the main evaluation index results of the data quality of the two are completely consistent;3) the RTKLIB software can display the satellite visibility, sky map and DOP value graphically, but no ionospheric delay error, ionospheric delay rate of change or satellite azimuth map; 4) combined TEQC with RTKLIB software can help to comprehensively and intuitively analyze the observation data quality, With a good analysis effect.