A diffractive optical element is designed,and the element can be used to modulate the incident azimuthally polarized Laguerre-Gaussian vector beam.A three-dimensional multipoint optical trapping structure(twin-optical chain)is obtained along optical axis near the focal plane of high numerical aperture focusing lens.The effects of the parameters of incident beam(the topological charge and the radial mode number of associated Laguerre polynomial and the interception ratio of incident beam),the structures of i...