Abstract: Changsha International Finance Center, the highest building under construction in Central China, is 452 meters high with structure of 93 ground layers and 5 underground layers and an embedded foundation depth of 42 meters. The rock in the building site 20 meters below the level is the Cretaceous argillaceous siltstone which is a kind of soft rock. The problem how to determine the characteristic values of subsoil bearing capacity of argillaceous siltstone is discussed by using the uniaxial compressive tests and loading tests with the diameter of 800 and 1130 mm. Through the tests and analyses, it is found that the bearing capacity evaluated by “Code for design of building foundation” (GB50007—2011) is quite lower than that from in-situ tests. In addition, the principles of determining the characteristic values of bearing capacity of soft rock iss put forward, which is deserved to be applied to practical problems such as those soft rocks.