The research of shutdown temperature drop rule in heated oil pipeline was the primary condition to ensure the safe restarts of the pipeline. According to the characteristics of service environments of submarine oil pipeline, based on the theory of porous media heat transfer, the submarine soil moistureheat coupling equation was established. Regularity of change of oil temperature was simulated in submarine pipeline during shutdown with time by software．The factors of effecting，such as thermal insulation layer, temperature of seepage flow and speed of seepage flow and so on，were analyzed，which decided a rational time for shutdown and provided a theoretical guidance for safe submarine oil pipeline startup．