Research conclusions: Under the condition that the coordinates discrepancy of CPⅢ points in adjacent two overlapping sections are lower than 3 mm after independent adjustment，the overlapping smooth results obtained with these two methods can meet the demand of checking the long and short waves of the track． From the angles of the survey theory，practice and application，the rigorous adjustment overlapping method is more reliable，its maneuverability of the overlapping data processing is better，and it is more available for the engineering survey．