The main factors that affect supply are as follows: the manufacturer's goal, the price of the commodity itself, the price of other related commodities, the change of production technology, the price of production factors, the government's policy and the manufacturer's expectation for the future. One is the price of the commodity itself. Because the manufacturer's goal is to maximize profits, under other given conditions, if the price of a commodity rises, the manufacturer will invest more production resources in the production of the commodity, thus increasing its supply; On the contrary, manufacturers will shift production resources to the production of other commodities with relatively high prices, thus reducing the supply of this commodity. The second is the production technology and management level. The improvement of production technology and management level can reduce production costs, even at the same price level, it will provide more products and increase supply. The third is the price of production factors. The price change of production factors directly affects the production cost of goods. Other things being equal, the factor price rises and the profit of the manufacturer falls; On the contrary, supply has increased. The fourth is the price of other commodities. If the relative prices between commodities change, resources will be redistributed, thus affecting the supply of commodities. The fifth is the expectation of the future. If the seller expects the commodity price to rise, he will hoard it and wait for the price to sell, thus reducing the short-term supply of the commodity. On the other hand, if the price is expected to fall, it will be sold in large quantities, which is an increase in short-term supply. In addition, other factors such as climate, number of manufacturers and time may also affect supply. If all the factors affecting the supply quantity are taken as independent variables and the supply quantity as dependent variables, then the dependence between the supply quantity of goods and these factors can be expressed by functional relations, which is called supply function.