The study aimed to identify the degree of practicing educational supervisors for the educational supervision, the degree of development of the teachers performance at the basic education schools and the relation between them AL-Dakhiliyah governorate in the Sultanate of Oman, and sought to identify the effect of the variables of (type, years of experience, In this study, the researcher used the descriptive approach, where a questionnaire was designed consisting of two axes: first the measures the degree of the practice of educational supervisors for the fields of educational supervision, and contains three areas: Supervisors supervising the implementation of professional teachers, practicing supervisors in the evaluation of the practices of professional teachers), and measures the progress of teachers' performance. It includes three areas: planning, class attitude , Personal characteristics). The questionnaire was distributed to the study population, and 262 questions were returned. As for the analysis of the statistical data and methods used, the data were entered into the (spss) program and analyzed using mean of arithmetic, standard deviations, alpha- Cronbach, T-analysis, and the Pearson correlation coefficient. It has reached the following conclusions: - The average degree of practicing educational supervisors for the fields of educational supervision from the point of view of teachers of basic education schools (intermediate), and the averages of the degree of development of the performance of teachers of basic education schools (large). - There were no statistically significant differences at the level of (α ≤ 0.05) for the degree of practicing educational supervisors for the fields of educational supervision attributed to (type, qualification). - There were no statistically significant differences at the level of significance (α ≤ 0.05) for the degree of the teacher's performance due to (type, qualification). - There were statistically significant differences at the level of significance (α ≤ 0.05) in the fields of supervisory supervision between the levels of years of experience for the benefit of those with experience (1 - 5) years, and the presence of significant differences at the level of significance (α ≤ 0.05) Descriptive for the axis of the development of teacher performance between levels of experience for the benefit of the owners of experience (1 - 5) years also. - The existence of a positive correlation relationship of statistical significance at level (α = 0.01) between the degree of the practice of educational supervisors for the areas of supervision and the degree of the evolution of teacher performance. - The absence of a correlation relationship at the level (α = 0.01) between the practice of the educational supervisor for the supervision of the contemplative implementation of the practices of professional teachers and the development of the performance of the teacher in his personal qualities. In light of the results of the study, the researcher made some recommendations, including: - Provide intensive training courses for school supervisors and their teachers, by educational specialists in the Sultanate, including the use of scientific method in solving educational problems. - The need to focus the educational supervisor in his classroom visit to the practices of professional teachers. - Provide physical, technical and technician facilities for teachers and supervisors to raise the level of performance.