The invention relates to an ultrathin 16MnDR steel plate for an LNG storage tank. Transverse and longitudinal test samples of the ultrathin 16MnDR steel plate have a tensile strength Rm of 490-620 Mpa, a yield strength Rel of greater than or equal to 315 MPa, and an elongation A of greater than or equal to 21%; and under the temperature of minus 40 DEG C, the impact absorption energy KV2 of the transverse impact test sample is greater or equal to 27 J; when the test sample is subjected to normal temperature bending under the conditions that D is equal to 2a and b is equal to 2a, the test sample has no crack after being bent for 180 degrees; and after being subjected to 5.0% elongation cold deformation followed by artificial aging under the temperature of 250 DEG C for 1 hour, the transverse and longitudinal impact test samples have the impact absorption energy KV2 of greater than or equal to 27 J at the temperature of minus 40 DEG C. The ultrathin 16MnDR steel plate is especially suitable for a wall plate of the large LNG storage tank, and has good low-temperature performance and long-term stable service performance; continuous casting billets are used for production and are subjected to H expansion in a covered slow cooling mode, so that the difficulty of H expansion of the thin steel plate is overcome; and the rough rolling and the controlled rolling of a steckel mill are adopted, so that the temperature uniformity of the steel plate during rolling and the temperature uniformity of the whole plate are guaranteed, the rolling control precision is improved, and particularly, the excessive temperature difference in the later period between the head of the plate and the tail of the plate is avoided.