An efficient model was developed by optimizing the terms of intermolecular potential and monomer rotations in the Hamiltonian, and then was applied to determine the global structures and rotational transitions of H2-AgCl complex. Based on this model, a detailed study of intramolecular effects were examined for intermolecuar vibrational modes, rotational transition frequencies, and spectroscopic parameters relative to those of rigid-rotorapproximation model. Firstly, the full-dimensional equilibrium geometry is determined to be (Re, r1e, r2e, & theta;1e, & theta;2e, & phi;e) = (2.370 & ANGS;, 0.7785 & ANGS;, 2.2579 & ANGS;, 90.0 degrees, 180.0 degrees, 0.0 degrees), and the averaged structure is determined to be (R & nu;, r1 & nu;, r2 & nu;, & theta;1 & nu;, & theta;2 & nu;, & phi;& nu;) = (2.436 & ANGS;, 0.7905 & ANGS;, 2.2604 & ANGS;, 76.4 degrees, 172.8 degrees, 0.0 degrees), which are in excellent agree with the available data of experimental observations. In addition, the available transitions were accurately predicted with the maximal percentage error of 0.05%. Based on the determined spectroscopic parameters, two perpendicular bands were predicted and will be helpful to guide the further investigations in the far infrared spectral region experimentally.