At first,according to the literature on the function of price discovery,futures prices are misunderstood by many scholars as unbiased estimates of future spot prices,while futures markets usually have been thought to bear the function of price discovery.Then,by analyzing the futures prices of investment assets and consumption assets respectively,futures prices are proved in theory that they are not unbiased estimates.Furthermore,the relationships between futures prices and spot prices are discussed.Finally,the function of price discovery is presented that it is of vital economic significance.