Successful applications of the single-loop optimization approach have been reported for resolving the distribution network reconfiguration problem. This approach was originally proposed as an intuitive heuristic method and has been understood so as well. This paper attempts to provide an analytical description and a systematic understanding about the approach via qualitative analysis. It formulates the problem as a nonlinear integer optimization problem which, if linearized, could be approximately represented by an integer LP (linear programming) problem. This understanding leads to the consideration of applying the concept of the simplex method normally used for solving LP problems, which, in turn, leads to the direct derivation of the single-loop optimization approach. This fact indicates that the single-loop optimization approach actually originates from the same technical principle as the simplex method. This paper also presents a simple and effective scheme to efficiently determine the switch exchanges within a loop for minimum line losses, and proposes a heuristic scheme to develop the optimal switch plan with minimum switch operations in order to accomplish the transition from the initial configuration to the optimal configuration. An example network is studied using the proposed approaches and satisfactory results are obtained.