A kind of method and equipment test the relation of polymer pressure, specific volume, temperature indirectly, uses the test equipment which is compose of the pressure medium mercury, seal liquid, sample room, pressure vessel, compression system, heat and cold system, pressure sensor, displacement sensor, thermoelectric couple and data processing system. This method using the character that the mercury and the seal liquid do not dissolve in each other, it can avoid the disadvantage that the mercury is toxic and is easy to volatilize in the indirect method of the polymer P-V-T test simply, at the same time, it has a series other merits such as can make the inner to reach high vacuum degree, to make the sample stress uniformly, the compress coefficient is small, impress pressure is direct, the measure precision is high and so on, it also resolves the problem that it vent the air in the presence of vacuum. It can use the relation of the polymer pressure-specific volume-temperature sets the mold technology parameter of the polymer product or design the module and do CAE analysis.