The concept of the product demand-forecasting is introduced and different methods of product demand-forecasting are compared. Taking a television plant for example, various predict models are used for forecasting the sales volume of product of the TV plant from the year of 2001 and 2003, compared with the actual sales volume. Then, the basic theory and the steps of establishing combined forecasting model are introduced in detail. Finally, the practical effects according to the scientific research item are given.