Compared to shallow water and onshore drilling, a number of technical difficulties are encountered in deepwater drilling and completion. Due to subsea high pressure and low temperature, hydrate has become a main threat to the safety of deepwater drilling and completion operation. Currently, OBM is the priority to prevent hydrate generation in deepwater drilling and completion. However, OBM is not environmental-friendly compared to WBM, so the latter was selected to use in ultra-deep water drilling. In view of the absence of similar experience, according to the actual situation of ultra-deep well in Lingshui block, the hydrate risk of 2 wells are simulated in order to identify hydrate generation condition; on the other hand, aiming at the risk of hydrate generation, proper hydrate inhibitor and drilling & completion fluid are selected. On the above basis, the matching technical scheme has been worked out. By the successful practice of deepwater drilling in Lingshui block, it is proved that WBM hydrate inhibition technology can well prevent hydrate generation during deepwater drilling operation and ensure operation safety, which has great reference and popularization value for the similar deep water well operation.