A through study of the postural stability of 40 subjects has been conducted with a stabilometer and the computer system. The subjects stand on the testing platform for 10 seconds and meanwhile the sum of frequency spectrum is being analyzed. The most men subjects maintain a little sway well within timits during the trials. The testing conditions include open eyes, close eyes, 10 degrees, 20 degrees, 30 degrees of platform inclination, transverse vision tracking, longitudinal vision tracking and vectorial vision tracking, All testing results show that there are unbalance differences between different age groups under different conditions.