The invention relates to a deep sea integrated variable ballast adjustment pump and an adjustment method thereof. The deep sea integrated variable ballast adjustment pump comprises a brushless directcurrent motor, a small flow gear oil pump and a sea water pump. A first rotating shaft of the brushless direct current motor is connected with a driving gear transmission shaft of the small flow gearoil pump, and the other end of the transmission shaft is connected with a second rotating shaft of the sea water pump. The sea water pump is internally divided into a low pressure sea water cavity anda high pressure sea water cavity. The low pressure sea water cavity communicates with the high pressure sea water cavity through a through hole. The second rotating shaft is connected with an inclined disc in the low pressure sea water cavity, and the inclined disc is connected with a plunger, wherein the plunger can penetrate the through hole. The low pressure sea water cavity and the high pressure sea water cavity are provided with a water inlet and a water outlet correspondingly. The water inlet and the water outlet are connected with a water pipeline. A compensation cavity of the small flow gear oil pump communicates with the brushless direct current motor and a compensation cavity of the sea water pump through pipes. The small flow gear oil pump is further connected with a hydraulicvalve on the water pipeline. The variable ballast adjustment pump is in the integrated design; the space is saved, and energy consumption of a system is lowered; meanwhile, coupling formed between thevariable ballast adjustment system and a hydraulic system is eliminated; and reliability of the system is improved.