The invention discloses a salt cavern oil storage surrounding rock self-balancing triaxial compression testing apparatus and method and belongs to the technical field of salt cavern oil storages. The apparatus comprises a cavity, a press rod, a piston, a sample, a first plug and a second plug; the inner wall of the cavity is provided with an inwardly raised first step, the cavity is divided by the first step into an upper cavity and a lower cavity , the sample is disposed in the lower cavity and extended straightly to the upper cavity, the press rod is dispose in the upper cavity and is loaded to the top of the sample, the piston is circular, the diameter of the sample is less than an inner diameter of the cavity at the first step and less than an outer diameter of the piston, the bottom of the sidewall of the lower cavity is provided with an oil incoming connector, the piston is axially provided with an oil outgoing passage, and an oil cavity may communicate with the outside through the oil incoming connector and/or the oil outgoing passage; the first plug is used for sealing the oil incoming connector, and the second plug is used for sealing the oil outgoing passage. The method is implemented based on the apparatus. The apparatus and method are provided in a triaxial pressure chamber and enable a triaxial compression test to be simulated in high-pressure crude oil or brine eroded environment.