This article presents the concept, principle and details of development of 1g physical model test equipments to investigate the failure behavior of rock mass surrounding a cavern under high internal for assessment of the stability of underground gas storage cavern. The paper describes the main components of the test system including a pressure system, synthetic rock, a support system, a detection method of rock response and a technique for fault simulation. The equipment is designed to cover both capsule and horizontal circular-tunnel shaped caverns for the continuum rock mass with and without fault. In each part of equipment development, the necessary aspects, main concept and technique to be used and detail on development are explained. In addition, some test results obtained by using this equipment are illustrated as an example to show that the developed device is effective and sufficient to be used in the studied topic. The presented results also indicate the necessity and advantage of using the developed device in the study, particularly a new understanding on failure behavior of rock mass in order to improve the numerical method for further study.