Abstract: In order to determine the relational expression of temperature, pressure and material intensity, the expression of is established in this paper. Theory analysis and the experiments showed that the melting point temperature of material is the function of pressure p. Higher the pressure of the material is, higher the melting point temperature. Hydrostatic pressure affects the material strength by affecting the melting point temperature of the materials. Under the same temperature, if the melting point is improved the material intensity will be improved. On the condition of high pressure or super-high pressure, material intensity will be equal or over its theory value, which shows that those defects existing in metals have closed at that time. The formula deduced in this paper provides the theoretical foundation for the downhole casing protection and prevention.