Abstract: Cellular detonation waves propagating through 15°, 20°, 30°, 40°, 45° and 60° smooth pipe bend were numerically simulated using the additional Runge-Kutta method, the 5th order weighted essentially non-oscillatory (WENO) scheme as well as the detailed elementary chemical reaction model comprised of 9 species and 48 elementary reactions in a stoichiometric H₂-O₂ mixture diluted by argon. The numerical simulation results show that when the regular cellular detonation wave propagates through the bend section, diffraction near the inner wall could cause increase in detonation cell size while detonation reflection occurring on the bottom wall could result in decrease in cell size. With bending angle increasing, continuous expansion wave leads to changes from critical detonation to failure near the inner wall. Under certain pressure, bend detonation at angle greater than 30°, the critical angle, could regain its regularity. There are two different modes of reflection, Mach reflection and regular reflection, due to the complexity of the bent pipe near the outer wall.