The embodiments of the present invention provide a control system and method for a medium-voltage photovoltaic distribution system. The medium-voltage photovoltaic distribution system includes N photovoltaic modules, N DC-DC converters, a DC-AC converter and a line-frequency transformer. Outputs of the N DC-DC converters are connected in parallel to a DC bus. The DC bus is connected to the DC-AC converter. The line-frequency transformer is configured to connect to a medium-voltage AC grid. The control system includes a bus voltage sampling circuit and N DC-DC converter control circuits corresponding to the N DC-DC converters respectively. Each DC-DC converter control circuit includes a bus voltage sampling circuit, a photovoltaic sampling circuit, a droop controller, a maximum power point tracking controller, an input voltage loop regulator and a pulse width modulation wave generating circuit. It can greatly simplify the communication system and improve the reliability of the control system that the DC bus voltage is used to replace a signal line for communication.