REBa₂Cu₃O_x (REBCO) tapes with high critical temperature, high critical current density, and preferably mechanical properties have been put into use in various industries. Nonetheless, its complex anisotropy and “error field” caused by the screening currents are still challenges for commercial applications. In this paper, the influence of with or without ferromagnetic substrate on the AC loss of superconducting composite tapes is first explored. It is discovered that the above and below superconducting tapes #1 and #3 have the screening effect on the middle superconducting tape #2. Then, the REBCO high-field coils were equated based on the anisotropic homogenization technique, and the distribution characteristics of the electromagnetic field, AC loss, and Lorentz force of the equivalent REBCO high-field coils are calculated. By investigating the performance characteristics of the central magnetic field, it is found that the screening current has an effect on the central magnetic field and critical current density of the coils. Moreover, the magnetic field induced by the screening current can reach a maximum of 0.8 T, which results in a 7.8% “error field” at the center of the REBCO high-field coils. Simultaneously, the screening current also reduces the critical current density at the top and bottom of the coils. Finally, the distribution law of current density and radial Lorentz force in different engineering turns in the fully charged state is investigated. The results prove that the Lorentz force generated by screening current is approximately 2.7 times greater than that of non-screening current (copper coils).