The invention relates to a liquefied natural gas filling truck tank. An inner support is fixed in an inner container. A thermal insulating layer is adhered to the surface of the inner container. An outer tank body is coaxially fixed outside the inner container through a plurality of positioning frames and the inner container. An outer support is fixed outside the outer tank body. A circulating vacuum pipe, a liquid outlet vacuum pipe and a gas returning vacuum pipe are fixed to the walls of the inner container and the outer tank body in a sealed mode. The circulating vacuum pipe, the liquid outlet vacuum pipe and the gas returning vacuum pipe are in sealing communication with an inner cavity of the inner container. A liquid outlet, a circulating opening and a gas returning opening of a filling truck are of a high-vacuum thermal-insulating low-temperature pipe structure; due to the high-vacuum thermal-insulating property of the vacuum pipes, the heat leakage and heat releasing of a pipeline system are reduced, and the static evaporation rate is effectively decreased.