In-plane bending is an advanced plastic processing technology which controls the uneven compressing plastic deformation of strip metal harmoniously and forces the strip metal to produce in-plane bending and to form an open circle. In-plane bending is divided into incremental and continuous process according to the loading manner. While much attention has been paid to the continuous in-plane bending techniques and achievements have been made at home and abroad, only limited experimental investigation has so for been done on incremental in-plane bending by overseas scholars. In this paper, a 3D finite element simulation based on the rigid-plastic principle is performed for incremental in-plane bending of pure aluminum sheet with width of 25 ~ 27.5 mm, thickness of 1.5 ~ 3 mm. Influences of technical parameters such as punch inclined angle αp, punch indentation s, thickness of strip t0, width of strip w0 and strip pitch p on the strip bending radius Rin are studied. The achievement of this study enriches the uneven deformation theory. It lays a theoretical foundation for generalization and industrialization of incremental in-plane bending and offers a new idea to the research and development of the advanced plastic processing technologies.