Abstract: The safety of subsea tree hydraulic flying leads is crucial for offshore oil and gas production and environmental protection. However, post-failure repairs or replacements often face prolonged delays due to constraints such as engineering vessel availability and supply cycles of spare parts. To enable rapid response to hydraulic flying lead failures, this research proposes a temporary isolation and wet-storage method based on remotely operated vehicle (ROV). Through optimized configuration of key components such as slings, clump weights, and buoy strings, combined with critical techniques like underwater deployment of ultra-long slings and surface lowering of heavy buoy strings, the failed flying lead is successfully isolated and suspended away from subsea facilities. This ensures continuous production from non-faulty wellheads, prevents potential environmental pollution from leaks, and creates favorable conditions for subsequent repairs or replacements. Practical engineering cases have verified the feasibility of this technology in complex deep-sea environments, reducing reliance on large engineering vessels and significantly shortening intervention cycles. The method provides key technical support for emergency repairs of subsea production systems and holds significant engineering value for enhancing emergency response capabilities in deep-sea oil and gas fields in China.