Abstract: In the determination of waters quality in desert ares Ion-selective electrode was used to determine the fiuorine content. The author describes briefly the principle, necessary conditions, and experimental resrlt experiments include; 1) Conditional experiment; 2） Comparison experiment; 3) Retrieve experiment; 4)Accuracy experiment and 5)Interference experiment. It is conclude that,in comparison with normal colorimetric analysis,Ion-selective electrods is,methodologically.simple and convenient and its result is satisfied.