Optical see-through head-mounted display (OST-HMD) calibration is crucial for virtual and real content alignment of augmented reality applications. Most conventional OST-HMD calibration methods heavily rely on manual alignment of virtual and real content to compute the transformation parameters of relevant coordinates. However, manual alignment is cumbersome and time-consuming, which limits the wide application of these methods. To address this issue, we propose a new alignment-free calibration method based on trajectory generation for robust OST-HMD calibration. There are three main steps of the proposed method: 1) Obtaining calibration image data from different coordinate spaces following predefined trajectories; 2) Calculate the transformation parameter from the real world to tracking camera and observation camera as well as the transformation parameter from virtual content to observation camera; 3) Derive the OST-HMD calibration parameters from above transformation parameters. The advantages of our method are: 1) Combined with the trajectories calibration mechanism, the proposed method can get more robust results than traditional approaches; 2) due to the precise geometry derivation from 3D-3D correspondences, it can naturally avoid manual alignment and obtain accurate calibration results without the requirement of any internal parameters of the virtual camera or the display parameters of OST-HMD devices. Extensive experiments show that the proposed method can achieve better calibration parameters than other methods on both accuracy and robustness.