The invention belongs to the field of deep sea operation tools and discloses a deep sea expanded shearing hydraulic tool. The deep sea expanded shearing hydraulic tool comprises a cylinder barrel, a booster pump, an end cover, a piston rod, a piston front block, two sets of expanded shearing assemblies and a handle, wherein the left end of the cylinder barrel is closed and provided with the booster pump; the end cover is installed at the right end of the cylinder barrel; the piston rod penetrates through the end cover and then is fixedly connected to the piston front block; and the two sets of expanded shearing assemblies are vertically symmetrical and comprise expanding arms, connection rods, strengthening corners and shearing blades. By selecting various high-strength alloy materials, improving the work pressure and optimizing the component structures, the small lightweight design is achieved, the underwater operation performance is improved to the greater extent, and as the blades are installed on the inner sides of the expanding arms, the shearing function is integrated on the forcible entry tool on the basis of common functions, and the adaptability of the forcible entry tool under the complex working conditions is greatly improved.