In response to the current demand for in-situ tesling in the fields of physies and materials for acontinuously controllable and adjustable temperature environment at both high and low temperatures, a passivevariable thermal resistanee strueture was designed with a G -M eryocooler as the cold source.This structure hasa high thermal conduetivity at low temperatures and a low thermal conduetivity at high temperatures, enablingthe sample temperature to be controlled and adjusted within a wide range of 6.2 .. 800 K without affecting thenormal operation of the G -M eryocooler,The system is simple in structure, stable and reliable in operation, andthe simulation and experimental verifieation results at both high and low temperatures are in good agreement.