VLF antennas are generally the small electric antennas that work in this frequency band, and their radiation efficiency is not high. In order to meet the requirements of long-distance communication, antennas often use multiple sets of antennas to ensure sufficient power capacity. Therefore, multiple sets of antennas synchronous tuning are very important. The multi-tuning method of multiple antennas is studied and the mutual coupling effect and tuning process are theoretically analyzed in the paper. The simplified multi-tuning valley antenna is verified by numerical simulation calculation, and consistent results have been obtained. This method can be provided a reference for the subsequent research and application of multi-tuned antennas.