The invention provides a continuously-adjustable sonic nozzle, which comprises a valve body 1 and a sonic nozzle 2, wherein the valve body 1 is connected with the sonic nozzle 2; the sonic nozzle 2 is a body of revolution; and an inner molding surface is partitioned into an equal-diameter inlet section 24, a circular-arc-shaped contraction section 25, an equal-diameter throat section 26 and a linear expansion section 27. The continuously-adjustable sonic nozzle is characterized by further comprising a plug cone 3, wherein the plug cone 3 is a body of revolution; the front end of the plug cone 3 is conical; the inlet 11 and the outer 12 of the valve body 1 are non-colinear; the outlet 12 of the valve body, the sonic nozzle 2 and the plug cone 3 are coaxial; and the plug cone 3 moves along the axis of the sonic nozzle 2 to change the minimum flow area of the circular-arc-shaped contraction section 25. Continuous adjustment of flow is realized; and the continuously-adjustable sonic nozzle has the characteristics of simple structure, high flow adjusting accuracy, high repeatability, high hysteresis, small operation force and small interference to flow fields.