In order to solve the problem that it is difficult to meet the feature recognition conditions during autonomous landing of unmanned aerial vehicle (UAV) during autonomous navigation, an optical flow-based altitude estimation and autonomous landing control strategy are proposed. According to the relationship between the height of the UAV and the vertical speed, a state-space model is established, and the small disturbance linearization system model is adopted to analyze the occurrence of self-excited oscillation during landing with a constant optical flow divergence through simulated landing. The simulation results show that under the given control gain, the stability of the control loop depends only on the height to the ground. When it is close to the ground, the control loop will self-oscillate. At this time, the airborne equipment can detect the oscillation and calculate height.