This study aimed to investigate the factors affecting students' achievements in Higher Education Institutions (HEI's). The study examined the relationships between under probation factors (Academic and personal), Students' motivations, and students' Achievements. To answer the research questions and test the study hypothesis, the research strategy, sample of population and data collections have been formulated to understand the under-probation factors that affect the students' achievement among HEIs in Oman and to examine the relationship between the research variables by using SPSS V.26. A questionnaire was conducted in A'Sharqiyah University with a random sampling approach. The study found finds that a significant relationship between under probation factors (academic and personal), students' motivations and students' achievements. Several recommendations were added in the last chapter to the decision making in HEIs proposing appropriate solutions that are consistent with their abilities and how the impact of providing these services affect directly the level of the student and their achievements. They should understand various critical academic and personal factors of the students' learning process and look on the students' satisfaction rate of the academic and non-academic services provided to the students and improve their services accordingly. This study is limited to one HEI, which is A'Sharqiyah University, and the survey would be more accurate if more than four HEIs participated. This study will provide HEIs with guidance on the factors that affect students' academic performance to raise the 'Students First' policy and determine the retention, progression and graduation rates. Key Words: Academic achievements, Under probation students, HEIs in Oman, academic advising, Students' motivations.