Infrastructure system is the backbone of the economy. However, large gap between demand and supply is observed in both developed and under-developed countries. Such gap is induced by two reasons, lack of fund invested in infrastructure procurement and low procurement efficiency due to corruption. Closing this gap can improve the economy of a country, help business to thrive and make citizens better off. This dissertation focuses on dealing with the low procurement efficiency in the context of private participation in infrastructure procurement. Based on literature review, stakeholder management, decentralization and agency problem is identified as three key fields in tackling corruption problem. Therefore, a framework incorporating these three fields is built. Based on hierarchical principal-agent model and highway pricing model, such a framework also bridges the engineering and economic models. Several vital problems in post-tender phase of infrastructure procurement are studied. Cost overrun is a problem plaguing all the infrastructure projects and using the framework, a model is established to distinguish the unintentional cost overrun due to technical uncertainty and intentional one induced by selfish motivation of official. The corruption in renegotiation of PPP projects is also investigated. Different scenarios based on the institutional monitoring and anti-corruption governmental contract are studied. This dissertation's contribution is three-fold: Firstly, a framework connecting two dimensions, that is, horizontally the stakeholder management, decentralization and agency problems and vertically the engineering and economic models, is established. Secondly, the corruption problems in post-tender phase of infrastructure project are addressed, given that previous research in such field is limited. Thirdly, Several important policy insights are provided in this dissertation.