<p>The artificial ground freezing (AGF) method is widely used as a special construction technique in underground engineering with complicated and sensitive environments. However, the method requires significant energy consumption in a long-term application, which results in high operation and maintenance costs. To ensure structural stability and construction safety, it is critical to predict its energy conversion and utilization. Therefore, this research provides a method to quickly calculate the energy conversion index (ECI) to analyze the energy conversion efficiency of oblique cross passage. Additionally, a thermo-mechanical coupling numerical model of this cross passage during freezing period was constructed based on the field monitoring data, considering the latent heat of phase change and the characteristics of orthotropic frost heaving deformation of the frozen soil. The development law of the freezing temperature field of the stratum was obtained, and the results were compared with the field observed results to verify the accuracy of the numerical method. Then, the development characteristics of the ECI curve were analyzed by calculating the total output energy, elastic strain energy and thermal energy during the freezing construction period, which showed that the ECI curve went through four phases (initial, rising, falling, and stable) with a peak of 0.623. Based on the ECI curves, constructive measures are proposed to improve the efficiency of energy conversion and utilization. The results show that the method can provide a theoretical basis for evaluating the energy efficiency and optimizing the freezing scheme during the freezing period of the cross passage.</p>