The study aimed to identify the degree of contribution of training patterns at the Specielised Institute for professional training of teachers in the professional development of public school teachers in the Sultanate of Oman. The study used a descriptive approach to achieve its objectives. A questionnaire was designing of two scales: training patterns with 27 statements and professional development areas with 19 statements. After checking the validity and reliability of the questionnaire, it was distributed to a sample of 384 male and female teachers in public school. The study showed that the degree of achievement of training patterns at the Specielised Institute was high from the teachers' perspective. The pattern of direct training was very high, and the patterns of learning in the work environment, and e-learning, were high. The findings showed that there are statistically significant differences at (α≤0.05) associated with the degree of achievement of training patterns dimension at the Specielised Institute linked to gender in favor of female in the direct training pattern. And there were no statistically significant differences linked to gender in the patterns of learning in the work environment, and e-learning. In addition, there were no statistically significant differences at (α≤0.05) ascribed to academic qualification, years of experience and training program in all the patterns. The findings also showed that the level of professional development of teachers who were trained at the Specielised Institute was high from their perspective. The personal dimension was very high, and the dimensions of specialization (scientific subject), vocational educational, and the administrative, were high. There were no statistically significant differences at (α≤0.05) ascribed to gender, academic qualification, years of experience, and training program in the teachers' estimates of level of professional development of teachers who were trained at the Specielised Institute from their perspective. The study revealed a statistically significant and positive correlation between all the training patterns scale and all the professional development areas scale. The correlation was strong, and the finding of liner regression analysis showed that degree of contribution of training patterns at the Specielised Institute can predict 77.7% of level of the professional development of public school teachers in the Sultanate of Oman. The study recommends continuing to increase the effectiveness of training and learning in the work environment by the trainers in accordance with the individual differences and the actual performance of the trainees at the specialized institute. Furthermore, continuously hiring local academic expertise in universities in the Sultanate of Oman by those concerned with the Specialized Institute in implementing workshops related to the skill of scientific research, and preparing reports on student behavior, for more mastery in this aspect.