Abstract: Hyperspherical coordinates are employed in describing collinear triatomic reactive scattering. Close-coupling differential equations are obtained by radial piece-wise semi-adiabatic expansion, and solved by first-order Magnus numerical propagation method with multistep exchange-set and reorthogonalization procedures. Applicating to H+H_2 and F+H_2 systems, we obtained good results which are in accordance with results of other method for the same systems.