To avoid the subjectivity of sample size design in the vibration experiment of uranium tailing dam,the method which describes the mean of absolute value of deviation angle is applied to restore the cumulative concentration curve of escaping radon.Sample subsets of varied capacity are obtained by isometric sampling with random starting point.The coefficient of determination of curve fitting is used to evaluate the representative ability to restore the experimental data sets.Without detriment to the accuracy of the experiment,the minimum sample size that cost less is obtained.The result shows th...