Abstract: High-rise and super-high-rise buildings in Chengdu are bound to be faced with medium-weathered red mudstone. In order to scientifically determine the load-bearing capacity of the medium-weathered mudstone of the Cretaceous group in the Chengdu area, a method for calculating the load-carrying capacity of this type of rock foundation under vertical load is proposed using a plate loading test with a binocular visual monitoring system. From the results, it can be seen that the mudstone foundation is mostly a thin-bedded structure with a bearing capacity of 1500~1966 kPa. The failure mode of the vertical load-bearing foundation can be reduced to that of thrust failure. In addition, the results of 50 in-situ load tests of the soft rock foundations and uniaxial compressive strength testing were compared in 10 engineering cases. Then, a revised calculation method was derived on the basis of the uniaxial compressive strength of the rock. The calculation of the new formula is similar to that of the plate loading tests.