A kind of cooperative guidance law based on the network synchronization principle is proposed for multi-missile three-dimensional coordinated attack. The synchronization algorithm gives out the speed in three directions, which are transformed to the command of total velocity and trajectory angles based on the kinematic relations. The controller designing is divided into three steps based on the backstepping method, which are designing of the speed and ballistic subsystem, the pneumatic angle subsystem and the angular rate subsystem respectively. The sliding mode control is used in every subsystem. The affection of aerodynamic parameters perturbation and external disturbance are estimated and compensated based on the extended state observer. Simulation results show the tracking features of controller and the coordinated attacking effect.