This Study aimed to identify the nature of the psychometric properties of the Thinking Style Inventory "short version" (TSI) to Sternberg and Wagner, "An Applied Study on the students of Sultan Qaboos University. The approach that was followed in this study was a descriptive one using appropriate statistical methods to answer the research's question, The sample of the study consisted of (1057) students (448 male and 609 female), who were selected from students at Sultan Qaboos University. The (TSI) List consisted of (13) a style of thinking styles (Legislative, Executive, Judicial, Monarchic, Hierarchic, Oligarchic, Anarchic, Global, Local, Liberal, Conservative, Internal, and External). To answer the questions of the study the psychometric measures of (TSI) was taken in to consideration. The validity of the inventory was verified by using two ways: Content Validity and Construct Validity by using methods such as: Comparison of Extreme Group, Internal Consistency Experiential. Validity (Convergent and discriminant validity), factoiral validity. In addition five factors founded, in all they explain (75.56%) of variation of the correlations matrice. The Reliability of the inventory was assured by using Cronbach's Alpha and test re- test method. Cronbach's Alpha was found between (0.53 – 0.72). Also the reliability coefficient by using test and re-test method was found between (0.55 -0.73.( The results were discussed in the light of the theoretical frame and the previous related studies. In addition, numbers of recommendations and suggestion have been reached.