Abstract: Methane may combine with water to form type I hydrate which consists of large or small cavities. That process is influenced by temperature. With molecular dynamics (MD) simulation method, the influence of temperature changes on hydrate crystals, their cavities and stability is discussed, under the simulation condition of constant temperature and constant volume (NVT). Crystal configuration, mean square displacement of oxygen atom, methane molecular displacement and interaction energy is analyzed through molecular simulation. Result shows that temperature has great influence on the stability of hydrate crystals, and it is mainly decided by the stability of large cavities. The structure and stability of large cavities is greatly affected by temperature. As temperature increases, the stability of large cavities decreases significantly, and the deformation of cavity structure increases. Collapse may even appear which causes the decomposition of hydrate. Temperature has less influence on the structure and stability of small cavities. The stability of small cavity in methane hydrate is better than that of large cavity under the same condition. Research results can provide theoretical basis for the control of methane hydrate formation process, rapid decomposition and stable storage of hydrate.