保理合同兼具融资、信用担保、信息提供、应收账款回收等多种功能于一身，属混合合同。保理合同的核心是应收账款转让。销售商以应收账款转让为对价获取融资，构成对应收账款的出售。应收账款转让在我国法制下应为事实行为，原因行为是销售商与保理商之间的保理合同。销售商应对转让的应收账款承担瑕疵担保义务。 销售商与保理商签订保理合同时，保理商即取代销售商成为债权人。通知债务人仅为对抗购货商的要件，不是应收账款转让的生效要件。应收账款移转给保理商，同时保证债权、担保物权、仲裁条款、延迟利息均一并发生移转。禁止债权转让的约款，对一般指名债权来说仅具有债权的效力，但不得对抗善意第三人。对于应收账款的转让，则宜设置例外，恶意受让人也可以受让应收账款。 应收账款转让通知为观念通知。即使未通知购货商，如果购货商已经知悉应收账款转让，即不得再向销售商清偿债务。购货商对保理商履行义务，仍以收到转让通知为标准。购货商在收到转让通知前主动向保理商清偿债务的，构成有效清偿。销售商和保理商均得向购货商发出转让通知。转让通知与诉讼时效之间的关系，宜类型化分别讨论。 购货商收到转让通知后，购货商对销售商的抗辩不论是发生在转让通知前还是转让通知后，均得向保理商主张。购货商以对销售商的债权向保理商主张抵销时，不必要求主动债权在转让通知到达时已届清偿期。在英美法上，购货商得以转让通知到达后始取得的主动债权主张抵销，在我国购货商基本上可以通过抗辩权的行使达到同一效果。 在解决债权双重转让的问题上，各国主要分别采优先次序原则和通知原则两种立法模式，我国法律原则上应采德国法优先次序原则的立法模式。现代经济生活中应收账款流转日益频繁，应收账款的自由流通具有重大的商业价值。根据权利公示的原理，应该考虑建立应收账款的公示机制，以妥善平衡交易的静的安全和动的安全

The business operation of factoring refers to the comprehensive financial services provided by the factor to the supplier, such as the trade financing, the full protection against the bad accounts, the administration of accounts receivable and the credit risk control, and the income account service. The supplier and the factor shall enter into the factoring contract according to which the supplier may or will assign to the factor receivables arising from contracts of the sales of goods made between the supplier and its buyer (debtor). As an untypical contract, the factoring contract have multiple functions of financing, protection against default by the buyer, collection of receivables and maintenance of accounts. The essence of the factoring contract is the assignment of receivables. The supplier transfers the receivable to the factor for trading financing, which constitutes the sales of receivables. In Chinese legal system, the assignment of receivable is a factual act, and the basis of the assignment of receivable is the factoring contract.The factor becomes the new creditor of the receivable as soon as the factoring contract was executed by the supplier and the factor. The notice to the buyer is not the constitutive requirement for the assignment. As the receivable is transferred to the factor, such accessory rights as the guaranty, the security interests, the arbitration clause and the deferred interests are also transfered. The assignment prohibition clause in the original contract is valid only between the parties concerned, and may not be used to protest against the bona fide parties. But as to the assignment of receivables, the willful assignees shall also be eligible to acquire the receivable. The assignment notice to the buyer is just a conception notice. With the awareness of assignment, the buyer is prohibited from paying the supplier. The buyer is obligated to pay the factor as soon as he receives the assignment notice, but he may also voluntarily pay the factor before the assignment notice is given. Both the supplier and the factor may notify the buyer of the receivable assignment, but the buyer before his payment is entitled to request the factor to provide the sufficient evidences to prove the receivable assignment. The assignment notice shall take the written form. In the case of ostensible assignment, the willful buyer is prohibited from avail himself of the ostensible defense. During certain circumstances, the suppler and the buyer may modify the original contract even after the assignment of receivable. After the buyer receives the assignment notice, he may claim to the factor its defenses against the suppler arising before or after the assignment notice. The buyer may execute an agreement giving up the defenses. The buyer may set off its claim in respect of the supplier against the factor, whether the voluntary claim matures when the buyer receives the assignment notice or not. In the common law system, the buyer may set off his claim arising after the assignment notice against the factor. The buyer may be equally protected by asserting defenses in Chinese legal system. Different legal systems have their own modes to deal with the double assignment by the supplier. The Chinese law shall take the path of the German mode. With the demand for the circulation of receivables, the system for the public notice of receivables shall be established.