Irregularcellular structurehas great potential to be considered in light-weight design field.However,the research on optimizing irregular cellular structures has not yet been reporteddue to the difficulties in their modeling technology.Based on the variable density topology optimization theory,an efficient method for optimizing the topology of irregular cellular structures fabricated through additive manufacturing processes is proposed.The proposed method utilizes tangent circles to automatically generate the main outline of irregular cellular structure.The topological layoutof each cellstructure is optimized using the relative density informationobtained from the proposed modified SIMP method.A mapping relationship between cell structure and relative densityelement is builtto determine the diameter of each cell structure.The results show that the irregular cellular structure can be optimized with the proposed method.The results of simulation and experimental test are similar for irregular cellular structure,which indicate that the maximum deformation value obtained using the modified Solid Isotropic Microstructures with Penalization (SIMP) approach is lower 5.4x 10-5 mm than that using the SIMP approach under the same under the same extal load.The proposed research provides the instruction to design the other irregular cellular structure.