Instructors are a core clement of higher agricultural education system.Many of the problems facing this system in Iran, root in the fact that the specialization of teaching in agriculture is not dealt with adequately in the process of specifying job requirements. Also we may refer to poor designing, implementation and evaluation of on-the job training courses for agricultural instructors. These two main problems, in turn, go back to the lack of an appropriate and comprehensive model of agricultural instructors professional competencies. Having the development of such a model as its broad objective, the present research aimed to I) identity the terms of learning of professional competencies, and 2)identity the situation triple domains of professional competencies (knowledge, attitude and psychomotor). The research was theoretically based on the model developed by Phipps (1972) and Cushman (1982) and it included four dimensions concerning instructional, scientific professional, and management-organization-curriculum planning.Totally 64 senior agricultural instructors were selected using random cluster sampling method. They were then interviewed using a questionnaire, whose validity was confirmed by eight education experts, and its reliability by Cronbachs alpha coefficient. The independent variable included individual and professional characteristics of instructors. The main findings of the research were as below:- Out of the total 105 competencies for agreement assessment and factors importance, 87 were agreed for instructors: instruction/teaching 46, scientific/ professiona 17, management/organization 17, and curriculum planning 17; - the priority of professional dimensions were instruction/teaching, curriculum planning, scientific/professional, and management/organizational; -the different dimensions of professional competencies ranked the same in terms of their importance in instructors performance and, - the most appropriate level for transferring professional competencies was during academic education and early on the job training.