The invention discloses an independent liquefied natural gas (LNG) experiment tank device, belongs to the technical field of LNG transport and in particular relates to a device for measuring temperature and pressure in an LNG liquid cargo tank under different thermal insulation layer thickness conditions. The device is used for measuring and recording the gas phase pressure, gas phase temperature, tank wall temperature and total tank mass change in the tank body in the natural LNG evaporation process. The experiment tank device comprises the tank body, a pipeline system and a base, wherein the tank body is coated with three thermal insulation layers; the two outermost layers can be sequentially uncovered, so that the thicknesses of the thermal insulation layers are changed; the pipeline system can realize LNG filling, automatic and manual BOG discharge, drying and inerting, pressure detection and temperature detection; the base can prevent possible damage of the tank body in the transport process. The device has the characteristics that the device is convenient to transport, comprehensive in functions and convenient to use, and an experiment can be performed under different thermal insulation layer thickness conditions.