随着高校对校园文化建设和精神文明建设的愈发重视，以及青年人自身对社会发展的愈发关注，大学校园公益社团呈现出蓬勃发展之势。各类志愿活动的开展，不仅对社会良好运行起到了积极的推动作用，而且促进了志愿者自身综合能力的提高。然而，大学生公益社团在发展过程中仍然存在着许多问题，如管理机制不健全、运作资金缺乏、活动重形式而轻实质、部分成员积极性低等。如何从组织层面出发来提高志愿者的工作投入，是本研究试图回答的核心问题。 在对国内外已有研究进行综述的基础上，从公共服务动机的视角出发，分析了组织管理因素对志愿者工作投入的作用机理，假设组织支持感和组织认同与志愿者工作投入呈正相关关系，并认为公共服务动机在这一关系中起中介作用。以北京师范大学的公益类社团的200名志愿者为调查样本，采用问卷调查法收集相应数据，通过探索性因子分析、相关分析、层次回归分析等技术手段，对上述理论模型进行了探讨。 研究表明，公共服务动机和工作投入量表具有较好的效度；大学生志愿者的工作投入在志愿服务时间上具有显著的差异，服务时间2学年及以上的志愿者工作投入程度最高，0.5学年的次之，服务时间为1学年的最低；组织支持感和组织认同对志愿者工作投入具有显著的正向影响，公共服务动机在其中起到部分中介作用。通过进一步研究发现，组织支持感和组织认同对工作投入的影响力，主要通过影响工作投入的子维度奉献来实现；其中，中介作用的产生主要通过公共服务动机的子维度公共利益承诺实现。 本研究揭示了组织支持感和组织认同对工作投入的正向影响，并验证了公共服务动机的中介作用，为公共服务动机的研究提供的新的理论视角；为公益类社团志愿者的管理和实践提供了简明的理论分析思路，并且为提高志愿者的工作投入提供了可行的管理建议。

Nowdays, colleges and universities are paying more attentions to the construction of campus culture and spiritual civilization. And the development of our society has caused the attention of young people.The communities of volunteers has showed vigorous development trend. But there are many problems in these public organizations, such as the chaos of the management mechanism, focusing on the form of activities but ignoring the essence, and the lack of enthusiasm. How to improve the work engagement of volunteers in organizational level, is the core problem of this research. On the basis of literature review and Starting with the perspective of public service motive, we have analyzed the mechanism of influences of the organizational factors on volunteers' work engagement. We assumed that the perceived organizational support and the organizational identification have a positive effect on work engagement. Using the data of the questionnaire among the volunteers in Beijing Normal University, this research applied the tools such as exploratory factor analysis, correlation analysis and hierarchical regression analysis to explore the research model. It has found from the research that the perceived organizational support and the organizational identification has a significant positive influence on the work engagement, and public service motivation undertakes part of the mediating effect between the perceived organizational support, the organizational identification and the work engagement. Furthermore, we found out that the mediating role of the public service motivation mainly works through public interest commitment, the sub-dimension of public service motivation.