The invention discloses a magnesium alloy anode rolled board and a preparing method and application thereof. The preparing method comprises the steps that magnesium, aluminum, lead, zinc and manganeseare put into a graphite crucible, argon is led in, stirred melt is casted in a stainless steel crucible in the a furnace, and an as-cast zinc and manganese modified AP65 magnesium alloy is obtained;under the argon protective atmosphere, the as-cast zinc and manganese modified AP65 magnesium alloy is subject to homogenizing annealing and then water quenching; rollers are preheated and heated, andan AP65 board is subject to intermediate annealing between two adjacent rolling passes, multi-pass hot rolling is carried out, the rolling pressing amount is controlled, and the magnesium alloy anoderolled board is obtained. Through alloying and rolling deforming, the microscopic structure of the AP65 magnesium alloy is regulated and controlled, under the open-circuit electric potential, good corrosion resistance is achieved, hydrogen evolution can be evenly dissolved and restrained through large-current density discharge, the negative discharge potential and the higher current efficiency can be achieved, and the magnesium alloy anode rolled board is suitable for being used a high-power ocean activated battery and magnesium-air battery anode material.