Abstract: Based on reliability design theory， taking the long-term concrete strength of transmission project foundation as research object，the drilling samples which were obtained in Zhejiang，Anhui，Ningxia，and Qinghai regions were subjected to compressive strength tests，the effects of regional and time factors on transmission concrete foundation strength were studied，then the probability distribution of foundation long-term strength was researched by combining with probability and statistics theory，and based on Bayesian statistical theory，conjugate distribution method was used to study the characteristic parameter of foundation long-term strength． The results showed that due to erosive environment，the mean value of long-term strength in different regions was presented with difference; long-term strength was declined with the increase of time，the longer service time，the larger standard deviation value，and the discreteness of strength value was more obvious． When the test samples in different regions，different service life but the same strength grade were collected，the probability characteristic of long-term strength is subjected to Gaussian distributions． The variation coefficients of C15 and C20 grade concrete foundation of transmission project were 0. 25 and 0. 26，respectively，improvement of the designed strength had a limited impact on its long-term strength enhancement under the influence of multiple factors．