In order to study the thrust coupling characteristics of unsteady parallel jet flows，a numerical simulation model was established to investigate the effects of jet velocity function，central axis distance，and time phase difference on the thrust coupling characteristics.The model was verified using experimental data.The results show that when the central axis distance is 1.5D （where D is the nozzle diameter），the average thrust ratio K between the dual‑nozzle and single‑nozzle jets increases with the increase in time phase difference within one jet cycle，with a maximum thrust loss of 8.53%.At larger time phase differences，K>1 occurs，indicating that the coupled thrust exhibits an enhancement effect.However，the maximum thrust enhancement is only 0.42%，suggesting that the thrust enhancement effect generated solely by the mutual induction between vortex rings is very weak.For central axis distances of 2.5D and 2.0D，the average thrust ratio K ranges from 0.994 5 to 0.997 3 and from 0.986 6 to 0.997 5，respectively，and both exhibit a trend of first decreasing and then increasing as the time phase difference increases.The research findings can provide a reference for the design of underwater unsteady propulsors.In particular，the new insights into thrust enhancement offer new ideas for the development of high‑efficiency underwater propulsors.