This Study aimed at revealing the Planning role's actual practices of the Secondary Schools' Principals in the Sultanate of Oman from their own viewpoints, their assistants/deputies and the administrative inspectors and recognizing the effect of sex, job, qualification, administrative experience, and training variables on the degree or extent of the secondary school Principals practice of their Planning role's responsibilities in the fields of planning the school work.. The sample of the study consisted of: 151 Secondary School Principals, 104 deputy Principals-and 34 administrative inspectors. To achieve the aim of the study, the researcher designed and developed a questionnaire for that planning role. In order to answer the study's questions, the meaning, standard deviation, T-test and One Way Analysis of variance were used. Then the Scheffe test was used for dimensional comparisons between pains of means. The study reached the following results: 1-The degreed extent of secondary school principals' practice of their planning role from the subject's' own viewpoints was high in the field of effective school discipline, administration affairs, and professional development of teachers, but average in the rest of the fields. : 2-There were some statistically significant differences concerning the sex variable which favoured females in the field of administration and financial resources organization, but there were no statistically significant differences in the other fields at the study. 3-As for the job variable, there were statistically significant differences in all fields. 4-There were statistically significant differences in the fields (Effective scholastic discipline administrative matters, teachers professional development, carrying out and improving the school curriculum, and an interactive relationship with the Tocal Community and environment) concerning the qualification variable. 5-As for the administrative experience variable, there were no significant differences in the fields of ( Pupils' affairs, Carrying out and Improving the School Curriculum, running the School building, running and Organizing financial resources and an interactive relationship with the environment and the local Community) but there were statistically significant differences in the rest of the fields. 6-There were statistically no significant differences concerning the training variable in all seven fields of the study.