The invention discloses a modular electrostatic dust collector, and aims at overcoming the defect that the existing electrostatic dust collection equipment cannot realize batch production and application. The modular design thought is provided and introduced; the batch production can be realized; during the installation and use, modules are used for splicing to adapt to different sizes of air opening structures. The modular electrostatic dust collector comprises a modular box body, an air inlet grid plate splicing structure and a dust collection device, wherein an air outlet grid is arranged at the bottom surface of the modular box body; an air inlet grid plate is arranged at the top surface; the modular box body is provided with an opening; the splicing structures are arranged at two sides of the modular box body; the adjacent modular box bodies can be spliced through the splicing structures; the dust collection device is arranged in a casing. During the daily work of equipment, a high-pressure high-frequency dust collection sterilization technology is used; indoor environment air can be subjected to dust removal and degerming treatment; during the installation and use, the modular splicing is used for adapting different sizes of air opening structures; the batch production and application are realized; the product cost is reduced; the product applicability is improved.