In consideration of the special problem of VTOL UAV deck landing, an autonomous ship landing guidance strategy based on on-board vision is proposed.The deficiency of the traditional 2D optical-flow velocity measurement method is overcome, and the 3D velocity vector of the target ship is estimated by using image spherical optical flow.Then, in order to solve the problem of insufficient control accuracy of landing trajectory of the traditional position control scheme, a guidance law based on Tau theory is employed for generating a desired trajectory that meets the constraints of soft landing in real time.In this phase, a trajectory tracking controller is designed taking the 3D velocity vector of UAV flight as the control quantity.Finally, based on Unity3D software, the visual simulation environment is developed, and semi-real, closed-loop simulation for verification is conducted by simulating different sea wave conditions.Compared with traditional trajectory planning schemes, the proposed scheme does not require complex optimization iterations and can meet both the real-time and accuracy requirements of deck landing.