The aim of this study was to construt and validate a scale for evaluating the tolerance of ambiguity for university students. The population of this study consisted of students of Islamic Azad University, Mobarakeh branch, and Payame Noor University of Mobarakeh. The sample of study included 400 persons which selected randomly. To investigate the construction validity of primary questionnaire, the statistical factor analysis was employed. The results from factor analysis with main component method and varimax circulation method showed that for 33-questions, 7 factors were obtained.These factors called: affective ambiguity, avoidance of complexity, avoidance of unregulated, avoidance of lake of risk - taking, avoidance of challenging, avoidance of aesthetical ambiguity and lake of being predicted.The total special value for 33 questions was equal to 14.73, KMO (sufficient of sampling), 0.86 and Bartletts test of spherical was 3795.18, with P<0.0001. The investigation of simultaneous validity Mac Donald 20 questions scale was used and obtained validity coefficient was equal to 0.54 (P<0.01).To study scalereli ability methods of Chronbach alpha and test- retest.were applied The obtained coefficients for total scale was 0.77 and 0.75, (P< 0.001) respectively. Also reliability coefficients for constructed scale factors were: affective ambiguity 0.80, avoidance of complexity 0.65, avoidance of unregulated 0.69, avoidance of lake of risk- taking 0.59, avoidance of challenging 0.54, avoidance of aesthetical ambiguity 0.55 and lake of being predicted 0.47, (P<0.001). The quality interpretation of results showed that 32.5% of subjects had high in tolerance of ambiguity and 30.29% were low.