The invention relates to a flow regulating device for ventilator testing. The flow regulating device comprises a testing air funnel, wherein an upper guide rail upright post and a lower guide rail upright post which extend in the axial direction of the testing air funnel are arranged at an outlet end of the testing air funnel; a raceway is manufactured on the inward surface of each of the upper guide rail upright post and the lower guide rail upright post in the length direction; a regulating wind cone of which the point end faces the outlet of the testing air funnel is arranged between the upper guide rail upright post and the lower guide rail upright post; a regulating screw is arranged in a cavity of the regulating wind cone; the regulating screw penetrates through a screw sleeve mounted at the tail part of the regulating wind cone to be mounted on a stepping motor; the screw sleeve is provided with an upper fixing seat and a lower fixing seat which extend in the radial direction; the upper fixing seat and the lower fixing seat are respectively connected with a first upper ball seat and a first lower ball seat through bolts; a first ball groove is manufactured in the end part of each of the first upper ball seat and the first lower ball seat; each first ball groove and the corresponding raceway form a first ball cavity; and a first ball is mounted in each first ball cavity, and rolls in the corresponding raceway. The flow regulating device has the advantages that the accuracy of air volume control is improved, and the air volume during the whole experimental process is enabled to be stable.