Abstract: Natural gas hydrate is a new alternative energy which is clean and high efficient. Baiyun Sag has favorable water depth, thermobaric and basic geological conditions for the accumulation of natural gas hydrate. Two sets of main sources rocks developed in the sag, i.e., Wenchang Formation and Enping Formation, of which TOC and Ro contents are high. The source rocks are gas-prone and have great potential of hydrocarbon generation, providing sufficient gas for hydrate accumulation. What's more, the sag has excellent migration conditions for hydrate accumulation. There are two types of migration pathways: the first one is faults connecting gas resources; the second one is diapirs. There are three kinds of migration patterns, i.e., singlefault migration, single-diapir migration, and diapir-before-fault migration. Gas hydrates are predicted in the sag for the first time and they are divided into two groups: hydrate deposits with BSR and hydrate deposits without BSR. Both single BSR hydrate deposits and double BSR hydrate deposits are discovered in the sag. Hydrate thickness of the sag is predicted to be ranging from 30m to 100m. Optimistically speaking, the hydrate resources is predicted to reach 60.4 trillion cubic meters, while it is conservatively predicted to be about 8.7 trillion cubic meters in the sag. It is shown that Baiyun Sag has broad prospect for exploration for natural gas hydrate

Key words: natural gas hydrate, accumulation, basic geological condition, BSR (Bottom Simulating Reflection), diapir, prediction of resources