Information technology outsourcing is one of the factors affecting the improvement of flexibility and dynamics of enterprises in the competitive environment. Also the study of the factors affecting its success has been always considered by business owners and the area of research. Professional experiences and research results consider that the success of IT "Information technology" outsourcing projects relates to the effective knowledge transfer and human factors. The human factors are influenced by the cultural and environmental context of the inside and outside of the organization. Hence, it is necessary to study the effectiveness of these variables in different cultural environments. This study investigates the effect of human factors including the customer motivation and vendor willingness on the success of IT outsourcing projects. For this purpose, the research hypotheses were developed and analyzed by the structural equation method. The result of a field study among 94 companies and organizations show the difference of the findings of this study with earlier findings in other countries. Based on the findings, the client motivation does not affect the knowledge transfer but the vendor willingness affects the customer motivation to knowledge transfer. This result can help the business owners to take appropriate approaches for achieving success in IT outsourcing projects.