The invention discloses a flue purification device modular layout method, and belongs to the field of energy conservation and environmental protection. Box body modules are arranged in a tail flue, the tail flue comprises a vertical flue and a horizontal flue, the horizontal flue part or the vertical flue part is selected at the tail flue to arrange the box body module, and elbows, reducers and special-shaped pipelines are avoided. The size of the box body modules is designed according to bearing, and meanwhile the smoke amount is considered. Considering the expansion of a box body, the flow field at an inlet is not influenced, and the box body modules can be connected in an arc-shaped, inferior arc-shaped, triangular and other modes. A supporting module is arranged in each box body module, a purification module is placed in each supporting module, the purification modules adopt a cylindrical tube bundle type structure, one, two or four cylindrical tube bundle type structures form a purification unit, and each purification unit can be relatively independently disassembled or assembled in the corresponding supporting module. Uniform flowing of airflow in a flue is facilitated, and generation of vortexes is reduced.