Abstract Background and Aim: Children with auditory processing disorders and impaired phonological working memory have difficulty in storing an accurate phonological representation of speech. Therefore, it is highly important to assess phonological working memory in this population. One of the methods in assessing phonological working memory is to use a non-sense syllable test. The aim of this study is to create a valid and reliable non-sense syllable test in order to evaluate phonological working memory in Persian speaking children with auditory processing disorders. Methods: In this cross sectional comparative study, 40 non-sense syllable words were developed according to the criteria of non-syllable word construction and under supervision of a linguistic specialist. The non-sense syllable test was assessed in 53 boys and 47 girls from 7 to 10 years of age. The content validity of the nonsense syllable words was assessed by experts. To evaluate the validity of the test, correlation between the results of the test and forward digit recall and backward digit recall tests were measured. The non-sense syllable test was performed twice to evaluate its reliability. Results: The validity of the non-sense syllable test was 95.5 (SD= 2). The correlation coefficient between nonsense syllable repetition, forward digit recall, and backward digit recall tests were 0.76 and 0.75 respectively (p< 0.001). The correlation coefficient between different performances of non-sense syllable tests was 0.8 (p< 0.001). Conclusion: These findings show that the non-sense syllable repetition test can be used to evaluate phonological working memory in Persian speaking children from 7-10 years of age.