The invention discloses a mobile shelter monitoring system and a battery energy storage system charge and discharge control method. The mobile shelter monitoring system is used for controlling an on-load tap switch of a line voltage regulator through monitoring a bus voltage at the output side, so as to change a no-load voltage ratio of an auto-transformer to realize line on-load automatic voltage regulation and improve a voltage of the tail end of a power distribution network. Meanwhile, the mobile shelter monitoring system is used for monitoring a battery energy storage state, controlling discharge when a battery energy storage system is in a peak load state and charge when the battery energy storage system is in a valley load state, and coordinating operation energy consumption of an energy storage bidirectional converter and the battery energy storage system, so that the safe, stable and reliable operation of the battery energy storage system is ensured on one hand, and the efficiency of the battery energy storage system is improved on the other hand. According to the monitoring system, joint control of the line voltage regulator and the battery energy storage system is realized, the advantage of the battery energy storage system is fully developed, the working range of the line voltage regulator is enlarged, and the problem of overlow voltage of the tail end of the power distribution network is effectively solved.