The purpose of this work is to numerically visualize the flow past forced oscillating square cylinder and investigate the effect of corner radius on flow induced forces. The finite volume code was applied to simulate the two dimensional flow past forced oscillating square cylinder with different radius to diameter ratios, (R/D =0 referring to a square cylinder with sharp edges andR/D=0.5 as a circular cylinder). The near wake of a square section cylinder with an increment ofR/D=0.1 was studied as the body undergoes a complete oscillatory cycle at lock-in condition, F=fe / fs=1 (where fe is the excitation frequency and fs is the vortex shedding frequency for the stationary cylinder). The computational model was validated for flow past oscillating cylinder with R/D=0.5 at frequency ratios F=0.5, 1.0 and 1.50, using as the lock-in and lock-out limits and the results shown good agreement. It was observed that computed value of Strouhal Number is nearly same for both stationary and oscillation case and a similar trend was observed, as R/D ratio increases. However, the results obtained from oscillation cylinder cases show the significant increase in root mean square value of lift coefficient (CL, RMS) and mean drag coefficient (CD) as compared to the stationary cylinder. Finally, It was found that the percentage increase ofCL, RMS is higher than CD in force oscillating condition for R/D=0, whereas both values decreases with the increase of R/D.