The passive flow control around a bluff body by two filaments symmetrically attached to the rear surface is numerically investigated in this paper.The bluff body is fixed,and two filaments are arranged in parallel form.The leading ends of two filaments are fixed at the bluff body and their trailing ends are free to flap.An improved immersed boundary-lattice Boltzmann method(IB-LBM)is employed in numerical simulation.The attachment angle between two filaments(α)varies from 0-90°.At the same attachment angle,different flexibility of filament(wr)is considered.Compared with the single bluff body,the use of two filaments can reduce both the lift coefficient and the drag coefficient.Moreover,the vortex shedding suppression also can be achieved.It is shown that both the attachment angle and the filament flexibility have the effect on the flow control.In particular,the maximum reduction of lift and drag coefficients occurs at α=90°.