In order to avoid the unobservable problem of passive tracking for single infrared search and track sensor, an active－passive joint tracking algorithm for a maneuvering target with IRST and Laser Ranger is developed. The current statistical model for tracking a maneuvering target is extended from 1D to 3D according to reference[1]. The state and nonlinear measurement equations for an arbitrary maneuvering target in 3D are educed. The angle measurements from IRST and the range measurements from LR are aligned in time. The correct measurement value is given. An extended adaptive Kalman filtering algorithm is used to simultaneously estimate the position, velocity and acceleration of a maneuvering target in 3D space. The results of simulation show that the presented algorithm is feasible and satisfactory.