Abstract Flow Induced Vibration (FIV) in Cross Flow around Triangular Array of Circular Cylinders with two-degree of freedom is studied numerically, where the cylinder was allowed to vibrate in the transverse (cross-flow) and longitudinal directions. Computational domain, Grid, Time step was optimized by performing Domain independent study, Grid independent study, Time step independent study. The computations were carried out at high Reynolds number range of 500, 1000, 2000, 5000 and 104 with multi-cylinder with change in upstream cylinder positions at 20°, 30°, 45° and 60° and varying pitch at 1.5D and 2D, Using FLUENT (version 6.3). Effects of Reynolds number on lift and drag force at various multi-cylinder arrangements were studied. The effects of Reynolds number on flow parameters such as drag coefficient lift coefficient, pressure coefficient, Strouhal number, lift and drag forces and vorticity were established. The lift and drag force on cylinder was used to solve the vibration equation, hence displacement of the cylinder which as validated with analytical as well as experimental results. A program was developed to calculate cylinder displacement and it has been employed successfully for the calculation and prediction of induced vibration of a circular cylinder.