Abstract: The high temperature gas in the flame working face of underground coal gasification (UCG) acts on the coal and rock mass around the gasification channel,which makes it in a unidirectional heating state.The thermal damage and thermal fracture in the normal direction of the coal and rock mass present an obvious gradient distribution law.In order to study the thermal damage characteristics of coal and rock mass under unidirectional high temperature and provide new experimental means,a unidirectional heating simulation test device for coal and rock mass was independently developed and designed.The device mainly includes four parts:heating and temperature control unit,temperature and thermal stress monitoring unit,acoustic emission monitoring unit,constraint and loading unit.The size of the sample used is 50 mm×100 mm,maximum one way heating temperature is 600 ℃,and the range of thermal stress monitoring is 5 MPa.The main functions,technical parameters,structure and key technologies of the test device,as well as the technical difficulties and solutions in the development process were introduced,and relevant experiments were carried out with the test device.The remarkable features of the test device include:① Realizing unidirectional high temperature heating and unidirectional constraint to simulate the heating state of coal and rock mass;② Realizing multi information synchronous monitoring of temperature,thermal stress and acoustic emission in the heating process,which is convenient for multi factor coupling analysis;③ The boundary heating temperature program is controllable,which can simulate different types of thermal boundary conditions.The unidirectional high temperature heating tests of sandstone were carried out by using the test device developed,which can reveal the characteristics of temperature,axial thermal stress and acoustic emission characteristics of thermal fracture in the height direction of coal and rock samples under unidirectional heating conditions,and further reveal the evolution law of thermal fracture of coal and rock bodies through dominant frequency analysis.The experimental device is suitable for exploring and studying the thermophysical phenomena and laws of coal and rock mass under the action of unidirectional high temperature heat source under the special environment of geothermal mining and underground coal gasification,and provides a new experimental means.