The study aimed to reveal the nature of the correlation between the five big factors of personality and job performance, identifying the most influential personality factors in job performance, identifying the significance of the differences in the five big factors of personality and career performance depending on gender variations, educational qualification, and occupational age. The sample consisted of 195 workers working in the governmental and official departments in Damascus countryside Governorate depending on the descriptive approach and using the five big factors of personality for Costa & McCrae (1992), Melhem Arabization (2009), and the job performance scale prepared by the researcher. Their validity and reliability were verified by using the appropriate scientific and statistical methods. The most important results: The correlation between: neuroticism, extroversion, openness to experience, kindness, conscience awakening and functionality -0.319, 0.515, 0.427, 0.493, 0.512, respectively and are indicative of 0.01. The results of multiple regression analysis showed that diastolic, neurotic, and conscientiousness contribute to job performance. There is a correlation between years of experience, the five Big factors of personality and job performance. There are no differences according to the educational qualification on the scale of the five big factors of personality and on the scale of job performance.