The present invention relates to an automatic ordering method and system for trading of stocks, bonds, items, futures, options, indexes, foreign currencies through data communication network, and more particularly to an automatic ordering method and system by computer according to certain conditions predetermined by an investor wherein the automatic ordering method for trading of stocks, bonds, items, futures, options, indexes, foreign currencies and the like through data communication network according to the present invention comprises the steps of: determining a trade-desired object in a computer system to input automatic trade conditions containing purchase and selling conditions; ordering purchase and selling according to the trade conditions through the data communication network; discriminating whether the purchase order and/or selling order has been contracted through the data communication network; and placing new purchase and/or selling orders through the data communication network according to the trade conditions predetermined by the computer when either the purchase order or the selling order is contracted.