This research was done with the aim of identifying and ranking how to set up the commitment contract and legal measures of the owner and the investor for the construction and completion of the project on time. This research was a descriptive survey study with a mixed method (quantitative and qualitative). In this research, the statistical population of North are active experts in the field of construction and familiar with legal contracts, and 8 people were selected using the available method. The ranking and weighting of the identified criteria were done using the fuzzy method. In the next step, the best contract was selected among the existing contracts using the obtained weights. The results of the ranking of the criteria using the Swarafazi method showed insufficient management skills with a weight of 0.55 in the first place, delay by contractors with a weight of 0.35 in the second place, delay in confirming the completed work with a weight of 0.24 in the third place. Material price fluctuations with a weight of 0.15 were identified as the most influential factors in project delays and costs in the fourth place. In the next step, the best contract between the contractor and the employer was selected using the obtained weights, and the results showed that the A8 contract was the best.