A leakproof atomizer includes a cigarette holder assembly, an atomization assembly, a heating assembly, and a liquid storage assembly. The liquid storage assembly is provided with an annular wall for dividing an internal cavity thereof into a first and a second liquid storage chambers in communication with each other via liquid holes in the annular wall. When the liquid storage assembly is assembled with the heating assembly and the cigarette holder assembly is disassembled from the liquid storage assembly, a bottom portion of the atomization assembly is separated from the heating assembly and hermetically connected with the liquid holes. When both the cigarette holder assembly and the heating assembly are assembled with the liquid storage assembly, the cigarette holder assembly presses downwards the atomization assembly, the atomization assembly is separated from the liquid holes, and the bottom portion of the atomization assembly is press-fitted with the heating assembly.