A electronic cigarette atomizer, comprising a liquid cartridge assembly for an electronic cigarette, the liquid cartridge assembly for an electronic cigarette comprising a liquid cartridge housing and a first plug fastened to each other, a liquid cartridge being disposed between the liquid cartridge housing and the first plug, wherein the first plug is provided with a through groove communicated with the liquid cartridge, two ends of liquid guide cotton pass through the through groove to extend into the liquid cartridge, a plurality of second protrusions for squeezing the liquid guide cotton are disposed in the through groove, and an air passing gap for supplementing air to the liquid cartridge is formed between adjacent second protrusions; wherein an atomization head assembly is clamped with a lower part of the liquid cartridge housing, the atomization head assembly comprises an outer sleeve, a rib and a first groove are disposed at the lower part of the liquid cartridge housing, a second groove and a first protrusion are disposed on the outer sleeve of the atomization head assembly, the liquid cartridge housing is inserted into the outer sleeve of the atomization head assembly, the rib is inserted in the second groove, and the first protrusion is buckled in the first groove; the outer sleeve is sleeved on a base, a lower part of the base is sleeved with a bottom cover, and an atomization sleeve is sleeved at middle parts of the base and the bottom cover; a first insulating seat, a resistance board and a second plug are disposed in the atomization sleeve from top to bottom; an ultrasonic atomization piece in contact with the liquid guide cotton is disposed on the first insulating seat, an atomization cavity is formed between the ultrasonic atomization piece and the first plug, the bottom cover is provided with a first air inlet, the base is provided with a vertical air inlet groove and a second air inlet communicated with each other, the atomization sleeve is inserted in the base so that the vertical air inlet groove forms a vertical air inlet channel, an upper part of the atomization sleeve is provided with a transverse air inlet groove communicated with the atomization cavity, and the first air inlet, the vertical air inlet channel and the transverse air inlet groove are communicated with each other to form an air inlet channel of the atomization cavity; and an air outlet channel for guiding smoke in the atomization cavity out is formed in the liquid cartridge assembly. wherein an atomization head assembly is clamped with a lower part of the liquid cartridge housing, the atomization head assembly comprises an outer sleeve, a rib and a first groove are disposed at the lower part of the liquid cartridge housing, a second groove and a first protrusion are disposed on the outer sleeve of the atomization head assembly, the liquid cartridge housing is inserted into the outer sleeve of the atomization head assembly, the rib is inserted in the second groove, and the first protrusion is buckled in the first groove; the outer sleeve is sleeved on a base, a lower part of the base is sleeved with a bottom cover, and an atomization sleeve is sleeved at middle parts of the base and the bottom cover; a first insulating seat, a resistance board and a second plug are disposed in the atomization sleeve from top to bottom; an ultrasonic atomization piece in contact with the liquid guide cotton is disposed on the first insulating seat, an atomization cavity is formed between the ultrasonic atomization piece and the first plug, the bottom cover is provided with a first air inlet, the base is provided with a vertical air inlet groove and a second air inlet communicated with each other, the atomization sleeve is inserted in the base so that the vertical air inlet groove forms a vertical air inlet channel, an upper part of the atomization sleeve is provided with a transverse air inlet groove communicated with the atomization cavity, and the first air inlet, the vertical air inlet channel and the transverse air inlet groove are communicated with each other to form an air inlet channel of the atomization cavity; and an air outlet channel for guiding smoke in the atomization cavity out is formed in the liquid cartridge assembly.