The invention relates to a passive constant temperature system applied to a thermal-insulating container. The passive constant temperature system comprises an outer shell, an inner wall and a cover, and is characterized in that a heat pipe and a phase-change material layer are arranged between the outer shell and the inner wall in turn; a vacuum chamber is also arranged between the outer shell and the inner wall; a handle is arranged on the outer shell; and a separating plate is arranged in the interior of the shell. Compared with a traditional thermal-insulating container, the passive constant temperature system applied to the thermal-insulating container according to the technical scheme has the advantages that a thermal-insulating function, energy conservation and environmental protection are realized without the usage of an external heat source because a phase-change material and the heat pipe are used together; articles in the container are subjected to uniform thermal-insulation due to the combined usage of the phase-change material and the heat pipe; selected materials are simple and common and are low in manufacturing cost; a thermal-insulating effect is excellent; a thermal-insulating time is long; the manufacturing is convenient and the use is simple; and the defects of the thermal-insulating container of the prior art that heat is quickly lost, the thermal-insulating effect is undesirable and the thermal-insulating effect is often realized by switching in the external heat source are overcome.