A true bipolar DC distribution network with droop control has problems with unreasonable load distribution and unbalanced positive and negative voltages. This will result in reduced converter utilization, increased additional losses, and affect system stability. In order to achieve reasonable load distribution and suppress the imbalance of positive and negative voltages, this paper proposes a distributed secondary power and voltage control strategy for a true bipolar DC distribution network. This strategy classifies voltage source converters (VSCs) according to the secondary control function, and exchanges information between adjacent VSCs. It iteratively obtains the corresponding power and voltage convergence values, and calculates the voltage regulation. This further changes the droop control reference voltage value, so as to achieve reasonable load distribution and suppress voltage imbalance. Finally, a true bipolar DC distribution network model is built in PSCAD/EMTDC, and the simulation results verify the effectiveness and reliability of the strategy. This work is supported by the General Program of National Natural Science Foundation of China (No. 51777066).