The invention belongs to the field of thermal treatment of steel plates, and relates to a high-pressure cooling device of a steel plate rolling type quenching machine and a cooling method. The devicecomprises a roller bed system, a water injecting system and a water supplying system, wherein the roller bed system comprises four rolling rollers, namely, a hydraulic rolling roller, a spiral rollingroller, an annular rolling roller, a common horizontal rolling roller; the functions of quickly draining water, partitioning surface flow rate of the steel plate and regularly exchanging heat while the deformation of the steel plate in a high-pressure cooling area is limited; the water injecting system comprises two narrow-seam injecting port sets and four inclined high-density injecting port sets, thus the high-intensity and high-uniformity quenching cooling can be realized; the water supplying system is capable of supplying accurate-flow-rate and stable-pressure cooling water to the injecting ports. With the adoption of the device, the problems of low heat exchanging controllability, low cooling uniformity and worsened plate shape in the steel plate quenching and cooling process can besolved; and the technical requirements on the structure performance and the shape of the quenched steel plate can be met.