The invention relates to the technical field of a battery, in particular to a model selection judgment method and judgment system of a power battery safety valve. The method comprises the following steps of calculating discharge rate of a gas instantaneously generated by thermal runaway of the battery according to battery weight before thermal runaway, battery weight after thermal runaway and discharge time; obtaining the highest pressure of a battery box according to design requirement of the battery box, and calculating discharge pressure of the safety valve according to the highest pressureof the battery box; calculating minimum discharge area of the battery box; calculating safety discharge quantity of the battery box according to the minimum discharge area and the flowing rate of thesafety valve; obtaining discharge quantity of the safety valve according to design requirement of the safety valve; and comparing the discharge quantity of the safety valve with the safety dischargequantity of the battery box, and replacing the safety valve with discharge quantity larger than the safety discharge quantity of the battery box. The method has the advantage of simplicity and is convenient to operate, and the safety of the battery and a person can be maintained.