Abstract: Based on the two-dimensional axisymmetric Euler equations, the initiation and detonation process of CH4/O2/N2 premixed gas induced by reflected focusing shock wave over the parabolic reflector was investigated numerically, using the nonorthogonal structured meshes and an improved reactive wave propagation algorithm. The flow field structures of detonation process were described. The effects of different compositions of premixed gas, incident shock wave intensities and reflector shapes on initiation and detonation were discussed. The results showed that the reflected focusing shock wave produced a local high temperature and high pressure region in the vicinity of the reflector apex, the region could ignite the premixed gas and lead to the detonation. The low diluted concentration of premixed gas, the high incident shock wave Mach number and the deeper reflector were of benefit to form detonation.