In this paper, we study in detail the specific convergence property of the physical-variable-based coarsening two-level iterative method (PCTL) algorithm based on the theory of algebraic multigrid method (AMG), and give a reasonable upper bound on the convergence factor, which provides a theoretical guarantee for the PCTL algorithm. Moreover, we also analyze the algebraic features that affect the convergence of the PCTL algorithm, such as diagonal dominance and coupling strength, hoping to provide theoretical guidance for the applications and algorithm optimization of the PCTL algorithm.