In the process of hot strip production, the control accruracy of the finish rolling temperature is an important indicator which affects quality of the products. As factors which have impact on the final finish rolling temperature are numerous and complicated, it's inaccurate and incomprehensive to analyze by looking at one single factor. With this in mind, a key variable extraction method in the hot rolling process based on importance of attributes is presented. This method, in the perspective of the entire decision-making system, analyzes each affected attributes, filter out the temperature attribute which doesn't affect the finish rolling temperature, determines the importance of each attribute. Based on the requirement of the temperature prediction accuracy and the characteristics of hot rolling process, the system extracts the key features of variables affecting the final finish rolling temperature. The application example demonstrates that this method can effectively extract the key features of variables that affect the final finish rolling temperature.