认罪认罚自愿性是贯穿认罪认罚从宽制度的生命线，是认罪认罚从宽制度的正当性基础，是保障被告人诉讼主体地位的应有之意，是实现诉讼公正的重要途径。它的重要性也得到了立法的认可。2018年10月26日，第十三届全国人民代表大会常务委员会第六次会议审议通过的《关于修改〈中华人民共和国刑事诉讼法〉的决定》（以下简称《刑事诉讼法修正案》）中，有五次提到“自愿”，自愿在认罪认罚从宽制度中的重要性可见一斑。认罪认罚自愿性保障机制的建立和完善是确保自愿性的前提，对其进行体系化研究一方面有助于我国贯彻落实和完善认罪认罚从宽制度，另一方面，也有助于丰富我国刑事法理论的相关研究。 研究认罪认罚自愿性保障机制，首先应当廓清认罪认罚自愿性的内涵，这是认罪认罚自愿性保障机制建立的逻辑起点。本文在分析理论界诸学说的基础上，总结出认罪认罚自愿性的基本内涵及其判断标准。 保障认罪认罚自愿性需要有完善的预防机制、监督机制和救济机制。本文立足于国情，并借鉴国外经验，从而总结出预防机制、监督机制和救济机制的构成要素。并根据司法实践中，这些制度在保障认罪认罚自愿性方面存在的问题，提出完善认罪认罚自愿性保障机制的建议。 具体而言，在预防机制方面，应当保障被追诉人享有知悉权、沉默权并获得有效的律师帮助，从而保障被追诉人具有一定的认知能力和自由意志，防止被追诉人因无知和被迫认罪认罚。在监督机制方面，应当确立讯问时律师在场制度、完善录音录像制度，以便规范讯问人员的讯问行为，防止追诉机关滥用权力，在审判阶段，应当强化法官对认罪认罚自愿性的实质审查，从而实现对审前讯问行为的监督，倒逼公安司法人员依法行使职权和保障被追诉人的诉讼权利。在救济机制方面，应当赋予被追诉人撤回权，并完善非法证据排除规则，从而为被追诉人认罪认罚后反悔提供程序救济机制，保障被追诉人不受非自愿认罪认罚的束缚，进而保证被追诉人认罪认罚自愿性得到充分的尊重。

It is of great importance to guarantee defendants to confess and accept the accused sentences voluntarily. Voluntariness is the legitimate foundation of the system of lenient punishment for guilty plea. It’s beneficial to guarantee the main role played by suspects in lawsuits and the litigation justice. The importance of voluntariness is accepted by legislation. On October 26,2018, the Sixth meeting of the Standing Committee of the 13th National People's Congress passed the decision that amended criminal procedure law of the people's republic of china (hereafter called criminal litigation law revised edition). “Voluntariness” is mentioned five times in it. Obviously, “voluntariness” is significant. Establishing and perfecting the guarantee mechanism is the premise to insure the voluntariness of confession and acceptance of accused sentences. The systematic study on it is not only can perfect the system of lenient punishment for guilty plea, but also can enrich some related criminal research. To study the guarantee mechanism of voluntariness of confession and acceptance of accused sentences, we should primarily define the connotation and denotation of voluntariness of confession and acceptance of accused sentences，which is a start to construct the guarantee mechanism. On the basis of analyzing the various theories, I conclude the judgment criteria of voluntariness. To guarantee the voluntariness of confession and acceptance of accused sentences, perfect prevention mechanism, surveillance mechanism and relief mechanism are necessary. All constitutional mechanism proposed by this article have our national conditions and foreign experience. According to the problems constitutional mechanism facts in the judicial practical, I propose advice that can perfect the guarantee mechanism of voluntariness of confession and acceptance of accused sentences. To protect people being prosecuted confess and accept the accused sentences from ignorance and force, we should assure that they have limited cognitive ability and free will. So, suspects must have the rights to information, the right to silence and the right to lawyer. To prevent the prosecution from abusing its power ，we need to set up the counsel-present system and a system that record and video simultaneously while interrogating to strengthen the supervision to course of interrogating. In trial stage, the judge can supervise whether the interrogation is lawful by strict review. The right of revocation and the exclusionary rule can provide a process relief to prevent people being prosecuted from being bound by involuntariness of confession and acceptance of accused sentences, which embody the respect to the accused’s voluntariness of confession and acceptance of accused sentences.