A method of preparing a polymer hollow particle, a low-specific gravity and monodispersed polymer hollow particle of various shapes prepared using the method, and a composite including the polymer hollow particle are provided. The method includes: a first step of providing, onto a substrate including a engraved pattern, at least one expandable particle comprising a foaming agent-containing expandable core and a thermoplastic polymer shell; a second step of removing an excess of the at least one expandable particle from a resulting product of the first step; a third step of expanding the at least one expandable particle in the engraved pattern of the substrate by thermally treating a resulting product of the second step; and a fourth step of separating, from the substrate, expanded hollow polymer particles which are a resulting product of the third step.