Three-dimensional Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are performed to investigate aerodynamic forces on a circular cylinder in linear shear at Reynolds numbers of Re=60-1000. The shear parameter , which is based on the velocity gradient, cylinder diameter and upstream mean velocity at the center plane of the cylinder, varies from 0 to 0.30. The movement of the stagnation point and separation points, and lift coefficients with shear parameter are studied. The results show that the stagnation point moves to the high-velocity side almost linearly with shear parameter, and this result mainly influences the aerodynamic forces acting on a circular cylinder in shear flow. Both the Reynolds number and shear parameter influence the movement of the stagnation point and separation point. The lift force increases with increasing shear parameter and acts from the high-velocity side to the low-velocity side.