Choosing the most suitable contract type depending on the characteristics of the project, project surroundings and project participants is important because of more favourable risk distribution and minimizing disputes during the construction process. Therefore, a model for selecting the optimal contracting method is developed in this graduate thesis. Model and software are created by applying the methodology of testing external and internal sources of risk, and the characteristics of the construction project. The software result is a risk table generated according to the user inputs for the construction project type model. The model identifies construction project risks and enables the determination of the optimal contracting method based on the payment method. A prerequisite for the successful implementation of the construction project is an appropriate selection of the contracting method and payment method. Contracting systems in civil engineering are explained regarding the type of building, the type of delivery of the building and the payment method. Each construction project has a certain dose of risk. The risk needs to be identified and assigned to the participant most capable of resolving it. The model can be upgraded for certain types of construction projects through detailed processing of construction project risks and deeper division of construction projects.