Business credit means the credit relationship between seller and buyer during the exchanges of goods. It is a result of common exchanges of goods and economic development. The business activities in Tang Dynasty were more active and varied than those in Wei&Jin Dynasties. According to the record of history, although payment in advance and delayed payment appeared during that period, business credit had not become common activities. It is in the northern and southern Song Dynasties that ancient Chinese business credit system came into being and developed into complete form. At that time the founding of this advanced and scientific economic policy promote the business economy of Song Dynasty to it’s prosperous time.