Abstract: The data treatment for the determination of U-Pb concordant age of zircon was very complex and difficult. Just for this reason, the program of data treatment for U-Pb concordant age was edited" with System III extended advanced BASIC language, and was available to HP200 series computers and HP9872 plotter. The function of the program involved modifying data on the screen with knob-cursor, least squares fitting of a straight line, calculating concordant age and its error, automatically plotting graph, data saving and access. It was fully proved that the program run flexibly and conveniently by using in a long period. The accurate reliable results and graph could be obtained fastly. Thus the level and efficiency of U-Pb data treatment was raised for a big step. Additionally, it was a successful trying to develop the function of HP200 series computers.