The invention discloses a piezoelectric ultrasonic atomizer, which comprises a metal diaphragm and a piezoelectric ceramic ring sheet in mutual connection, wherein the outer diameter of the piezoelectric ceramic ring sheet is smaller than or equal to the diameter of the metal diaphragm, a group of atomization holes are formed in the metal diaphragm and are positioned in the through hole region of the piezoelectric ceramic ring sheet, the longitudinal cross sections of the atomization holes in the group of atomization holes are in a cone shape, the opening diameter of one end facing the through hole is smaller than the opening diameter of the other end, and in addition, the spaces of any three adjacent atomization holes are identical or similar. The atomization holes meet the requirement that x is smaller than 1.2d1 but greater than 0.7d1, and in addition, the area of the atomization hole region meets a formula that A1=(30 percent to 45 percent)S, wherein d1 is the diameter of the opening of the atomization hole back to the through hole, x is the space of any three adjacent atomization holes, A1 is the total area of the atomization hole back to the through hole, and S is the distribution region area of the atomization holes. The piezoelectric ultrasonic atomizer has the advantages that through the arrangement of the atomizer, the problem of unstable atomization effect caused by design blindness of the atomizer is avoided, in addition, the service life of the atomizer is relatively prolonged, and the use cost is reduced.