Abstract: Analyzing the performance of program is the basis of understanding the behaviors of programs. It is important to find the performance bottlenecks and learn the utilization of hardware and software resource. In the performance evaluation of parallel computing system, the performance characters of the application cannot be analyzed completely because of the restriction of the time and the space. An effective method is analyzing the performance characters of part of the application codes, and regarding them as the performance characters of the whole applications. In this paper, a method of analyzing the performance of the programs based on sampling is put forward. Furthermore, a profiler named SamplePro based on sample theory is developed. Compared with other methods under the condition of the same sample error, this technique can effectively reduce the needed instruction numbers, which means only 1%～3% instructions are used to achieve less than 3% analyzing error.