Abstract: For the steady-state identification of the key variables in the steady-state optimization,a determination method was proposed for the steady-state identification of sample data based on the hypothesis testing.The method could realize the data steady-state identification of the isolated heat-pipe heat exchange system.Then,experiments were carried out by the practical data with normal distribution characteristics.The data steady-state was determined by judging the change of sample variance.Finally,it was found that the optimization cycle must be greater than 4 minutes.