To achieve a smooth autonomous landing of the intermeshing-rotor unmanned helicopter in the presence of GPS signal interference， the TAG36H11 image from the AprilTags visual fiducial system was used as the landing landmark. A vision assisted autonomous landing control system for the intermeshing-rotor unmanned helicopter was designed based on this landmark. The process involved image pre-processing of the landing landmark， followed by the extraction of feature information using Canny edge detection， Hough transform straight line detection， and rectangle detection. The system then solved for the relative position and attitude of the unmanned helicopter using camera imaging principles and coordinate system conversion. An algorithm to determine the yaw angle using Hough transform linear detection was proposed， specifically for scenarios with GPS signal interference. The control system incorporated a cascade PID control structure， including a square root controller in position control to limit the desired position and maximum acceleration of the helicopter. In addition， an intermeshing-rotor unmanned helicopter attitude control mechanism was designed， which adjusted the cyclic pitch of the intermeshing-rotor by controlling the swashplate angle with six digital servos. This mechanism was pivotal in altering the flight attitude of unmanned helicopters. The system's effectiveness was verified through simulations with the Mission Planner flight control ground station， which combined the vision processing system with the flight control system. These simulations show that the vision-assisted flight control system can accurately track the desired position of the unmanned helicopter. After experimental verification， it is found that the attitude angle offset is controlled within 4° and the position offset within 0.05 m， demonstrating the system's capability to realize the intermeshing-rotor unmanned helicopter's vision-assisted autonomous landing.