The invention discloses a method for reducing the dosage of caustic solvent in nickel concentrate atmospheric straight dipping, belonging to the field of non-ferrous metal hydrometallurgy. The method comprises the following steps: grinding nickel concentrate to ensure that the grain size of 90% of nickel concentrate particles is 0.053-0.75mm, mixing the nickel concentrate with water in a weight ratio of 5-30:1 evenly to obtain ore pulp, placing the ore pulp in a stainless steel reaction container, adding concentrated nitric acid of which weight ratio to nickel concentrate is 0.75-1.5:1 and finally leaching for 60min under the action of ultrasonic wave of which frequency is 20.02 kHz and power is 50-150W, wherein when the leaching efficiency of nickel is up to 98-99%, the dosage of causticnitric acid can be reduced by 30-40% compared with that of caustic nitric acid obtained by using mechanical agitation for leaching under the equal leaching efficiency and time and higher temperature (95 DEG C). The invention greatly reduces the dosage of industrial caustic acid-nitric acid; the dosage of nitric acid obtained by using ultrasonic wave agitation instead of conventional mechanical agitation is decreased by 30-40% under the experimental condition which is more beneficial for mechanical agitation leaching; and the reaction can be performed at normal pressure under ultrasonic wave without special heating and the concentrate is not needed to pretreat.