Flow over a bluff body usually creates a large region of separated flow and a massive unsteady wake region downstream and they have susceptibility to flow-induced vibration. Vortex shedding observed in the wake of these bodies generates unsteady (periodic) lift and drag forces. Flow-induced vibrations and generation of the fluctuating forces are major problems in most of flow systems in engineering and industrial applications. If these phenomena are not considered in design of an engineering structure, it can be demolished the structure due to oscillations formed in its natural frequencies. Thus, the elimination or reduction of the fluctuating forces and vortex shedding from such bodies by the application of the various passive or active flow-control methods is necessary. The aim of this study is to reduce the fluid forces acting on a bluff body by an active control. The effects of uniform suction and blowing through the walls of a square cylinder at incidence (between 0 to 45 degree) on the vortex shedding, wake flow and heat transfer are studied via a numerical investigation for laminar regime (Re=100-200) and turbulent regime (Re=10000, 22000), Pr=0.7. To solve the unsteady governing equations, all simulations were performed with a finite-volume code based on a collocated grid arrangement. To find the optimum conditions, where the suppression of the vortex shedding is occurred and the maximum reduction on the forces and their fluctuations is achieved, some simple cases are examined. In these cases, the influence of the uniform blowing and suction only through one surface is studied for angles less than 45 degree and two surfaces at 45 degree. Based on the obtained advantages of these simple cases, different combinations of the suction and blowing on the cylinder sides are considered and an optimum case is introduced. The results of this study for laminar case showed that the optimum case for cylinder at 45 degree is achieved when the suction is applied on the front surfaces and the blowing is employed on the rear surfaces. For angles between zero and 45 degrees, the optimum case is obtained when the suction is applied on the top surface and blowing is employed on the other faces. In this study, the effect of Reynolds numbers and angle of incidence on the results for the optimum configuration is also investigated for laminar flow. In turbulent flow over cylinder at 45 degree, the results showed that the forces are sharply reduced when the active control is employed. Keywords Active Control; suction and blowing; heat transfer; square cylinder at incidence; vortex shedding