The aim of this study is to explore the perceptions of Female Second Domain Teacher (Science and Maths) about sex difference. It also aims to investigate the influence of teaching experience variable and major in Bachelor variable on these perceptions. The sample of the study consists of (416) Female Second Domain Teacher in Sultanate of Oman in the school year 2019/2020.The perceptions scale about sex difference was applied on those teachers. Beside, Semi-Structured interview was conducted on sample of (15) teachers. The researcher developed two instruments to achieve the aims of this study. The first instrument, which was the teacher perceptions scale of sex difference consisted of (40), items distributed on 4 domains which are: difference in cognitive abilities, teacher interaction in the classroom, the physical classroom environment, and teaching and learning strategies and activities. The second instrument, which was Semi-Structured, interview consisted of (10) questions for a deep understanding of the phenomenon. The validity was examined by a panel of (11) judges. The reliability was examined by alpha Cronbach for internal consistency and the reliability coefficient for the perceptions scale was (0,92). The result of the study indicated that the perceptions of the second domain teachers of sex difference are medium. The mean of the sample responses to the scale was (3,65 out of 5). The result also indicated that there was no statistically significant difference at (alpha=0,05) on the means of teachers perceptions attributed to the teaching experience while was statistically significant difference at (alpha=0,05) on the means of teachers perceptions attributed to major in Bachelor. The benefit was for teachers with a Bachelor's degree in a second domain. In the light of the above results, the study recommends conducting study to analyze the Cambridge curricula and the extent of their consideration of gender differences and to conduct a study to show the perceptions of male and female students on the topic of gender differences, The study suggests conducting experimental studies on the effect of the teacher's gender on academic achievement.