Abstract：According to the need of revising the current power industry standard in China：“Design Code for Steel Penstocks of Hydropower Stations”，and the theory of structural reliability，research is made on the statistical characteristics of sharing ratio of internal pressure in bedrock for embedded penstocks of hydropower stations. The probability distribution function and the corresponding statistical parameters of sharing ratio of internal pressure in bedrock for embedded penstocks in terms of design reference period are determined by analyzing measured data collected respectively from domestic and foreign hydropower stations and adopting K-S and A-D test methods in statistical mathematics to make statistical analysis and distribution hypothesis verification. The test probability distribution function is testified to be the logarithm normal probability distribution. These results not only provide necessary basic data for the revision of the current steel penstocks code of China，but also have significant reference value to the design of embedded penstocks of hydropower stations.
