This aim of this research was to identify parental treatment styles and their relation to psychological harmony among year twelve female students in The Governorate of Al Dakhiliyah. The researcher used the descriptive method to conduct this research on a random sample of 100 female students aged between (17-18) years. The researcher used the scale of parental treatment types adapted from the measure of Abdulmaqsоd (2007), and the scale of psychological harmony adapted from the measure of Hussein (2011). Results of the study indicated that the prevalence of parental treatment methods (Democratic) was significantly observed, as it appeared that the field of Family harmony is the most common, followed by social harmony then by the psychological harmony and finally by health harmony. Results have indicated that there is a correlation between parental treatment styles and psychological harmony among year twelve female students. The value of the correlation coefficient between parental treatment styles and psychological harmony was 0.76, indicating the positive correlation between variables, meaning that whenever the parental style was positive, the psychological harmony was high, The study concluded that according to Pearson correlation coefficient analysis, there was a negative weak correlation between the undetermined parental styles and psychological harmony among female students at 0.46. with no statistical significance at the level of 1.15. This means that whenever the treatment styles of parents were not determined, the psychological harmony level as perceived by the sample of the study was low. Non-significant results could be attributed to the small sample of the study plus to the age of the students which were around the same.