Abstract: Wind tunnel experiments were conducted to investigate strake sweep angle effects on the flow over a slender body at subcritical Reynolds number Re=150 000 and α=50°. The slender body model has an optional device named strakes installed on the model. The sweep angle of the strake leading edges can be varied. Pressure measurements and particle image velocimetry were performed to study how the leading edge sweep angle of the strakes influence the pressure distribution and the wake over the model. The results show that, the strake vortices locate at a shorter distance to the model surface in front of the strakes and the vortices are symmetric about the model's longitudinal center plane. It would symmetrize the wake over the model's forebody and reduce the corresponding sectional side force. The strakes with larger sweep angle raise this tendency. The strake vortices couple with the asymmetric vortices from the forebody and gradually become asymmetric at the strake rear. At the downstream of the strakes, the induction effect of the strake vortices weakens as the sweep angle increases. It would result in the asymmetry of the pressure distribution on the body surface, which produces larger local side force.