In medium voltage power line communication, an adaptive impedance matching method for medium voltage power line carrier communication is proposed to solve the problem that line impedance mismatch caused by the variety and quantity of complex electrical components will influence the quality of communication. First, a model of a medium voltage impedance matching system is established, and a π-type adaptive impedance matching circuit is proposed based on the model. Then, an objective function conforming to the impedance conjugate matching principle is designed according to the circuit, and the optimal component parameters are found out by PID-based search algorithm (PSA) based on proportional integral differential (PID) to achieve the optimal objective function. Finally, based on this model, the advantages and disadvantages of PSA, particle swarm optimization (PSO) and genetic algorithms (GA) are simulated and analyzed. The results show that the PSA is superior to PSO and GA algorithms in terms of convergence speed and optimization accuracy, and can effectively realize impedance matching and improve carrier communication quality. This provides a feasible scheme for further research on medium voltage power line communication.