Abstract: Traditional structural optimization methods do not take full account of the process constraints from additive manufacturing.Manufacturing process and post-processing will become more difficult if the optimized model has process geometric characteristics such as large overhangs and closed cavities.This paper presents bidirectional evolutionary structural optimization method with regional penalty factor.It makes optimized results printable by considering process feature constraints.Regional penalty factors were defined according to the region where elements belonged to.Factors should gradually increase from outer toward inner core while meshing.Stress of the element would be penalized with the factor to decide its retention or deletion after finite element analysis.Compared with traditional bidirectional evolutionary structural optimization method by numeric experiments,the method can change the morphology of cavity,reduce overhang area,balance the stress distribution of the model,and improve the printable effect of the topology optimization model.