Gas hydrate, a new kind energy resources discoverd over the past ten years, has aroused much attention from many countries around the globe, because the gas hydrate has played a very important role in energy resources exploration, submarine geohazards precaution, and changes in global climate. So far, gas hydrates have been found in about sixty places on continental margins and polar regions in the world, but the majority of them is recognized by all kinds of indirect indicators owing to their limited existence conditions, only minority of them is collected. Thereby, the indirect marks of gas hydrates play an important role in exploration of the clathrate compounds, and the authors discuss them.