<p>To investigate the dynamic characteristics of asymmetrical gears under different rotation states, this paper designs asymmetrical tooth profiles based on the tooth tip thickness constraint method and analyzes the influence of tooth number on the variation range of tooth thickness and pressure angles. Time-varying mesh stiffness (TVMS) models for driving states on both the large and standard pressure-angle sides are established. A lumped parameter dynamic model is developed to analyze system responses, and vibration experiments are performed on an FZG closed power flow test rig for validation. Theoretical and experimental results show that tooth profile parameters and rotation direction couple to affect resonance distribution and frequency-domain responses. Under the standard pressure-angle driving condition, the system exhibits a higher natural frequency and more stable vibration, while under the large pressure-angle driving condition, the frequency response becomes more sensitive to tooth profile variations. The novelty of this work lies in developing a comprehensive analytical-experimental framework that integrates tooth geometry design, stiffness modeling, and dynamic validation for bidirectional asymmetric gears. The findings reveal the coupling mechanism between pressure-angle asymmetry and rotation direction, providing practical guidance for designing low-vibration and high-stiffness gear transmission systems applicable to reversible mechanical drives.</p>