This paper develops EOQ models under delay in payments to three-level EOQ model,assumed that supplier offers retailer order-size-dependent delay in payments and retailer also gives customer a fixed period of delay in payments.

This paper points out that the price, quality, the level of supplying on time, the level of after-sales service and so on can be regarded as resources that the suppliers can provide, and proposes a concept called the comprehensive level of resources exploitation which can be used to evaluate the comprehensive effect of order quantities allocation of one product between several suppliers.

Through the comparisons of every two factors, the fuzzy judgement matrix was dotained, and then the weights of the factors which influence the purchasing quality and the order of the schemes were determined by using FAHP.

In order to ensure the specialized books quantity and increase the aim of purchasing books,a analysis model of purchasing quality for specialized books in the university library was established in this paper.

The purchaser s optimal purchase rate is discussed and the mathematics impression is worked out by means of mathematics according to the request of the purchase quality.