The invention provides an inventory management system which comprises at least one terminal computer, one database and one server; the terminal computer is used to have management operation on inventory information; the database is used to store the inventory information; the server is connected with the terminal computer and the database respectively through network. The server comprises an inventory information import module and an inventory information processing module; the inventory information import module is used to import all the inventory information which is to be treated with processing to the database; through adopting the method of mathematical statistics on the utilization rate of raw material, the inventory information processing module determines the standard deviation of raw material in a certain time, combines the safety factor of raw material and the average delivery time of suppliers to forecast safety stock in a certain future time, inquires the current inventory, judges whether the current inventory relative to the safety inventory is excessive or inadequate, produces an inventory state table with a warning mark and deliveries the state table to a relative external system and the suppliers.