For the problem of multi-missiles intercepting single maneuvering target, the cooperative guidance law with impact time and angle constraints was presented. Firstly, considering the system dynamics equation and the multi-agent consensus algorithm, a second order sliding mode controller along the line of sight(LOS) was proposed based on integral sliding mode control concept to guarantee salvo interception. Then an higher order sliding mode observer (HOSMO) was designed to estimate external disturbances of the perpendicular to the LOS. In addition, the sliding mode controller with HOSMO was proposed to guarantee the LOS angles converge to desired commands and the LOS angle rates converge to zero. Moreover, the stability of the two subsystem channels were proved by Lyapunov theorem. Simulation results illustrate the effectiveness of the proposed cooperative guidance law.