Given the circumstances of high price and limited fund, purchase-decision is of great importance for library personnel to meet the demand of readers. Here we analyzed various factors that influence the price of original foreign language books, as well as the policy of the foreign language book supplier. The analysis is to provide useful reference for wise purchasing of original foreign language books. At the same time, the libraries should give a reasonable profit margin to the foreign language book supplier, in order to get better service. The libraries and the foreign language book suppliers represent different economic interests, but they are the partner of foreign language books which from producers to user, both sides are in the works to meet the needs of the readers. Therefore, they should strive for long-term cooperation, to achieve a win-win situation.