Objective To investigate the SCL-90 measurement inaccuracy caused by understanding of words.Method 172 freshmen aere requested to answer 45 questions

the first half of SCL-90

and designate values for the options.Evaluating-diversities of qualifiers range from 0 to 10.According to the scores calculational methods in SCL-90

each scale scores are calculated.The scores difference are analyzed between evaluating-diversities and designating values according to isometry principle.Results Two kinds of calculational methods are corresponded closely to each other（P<0.01）.There is significant difference in understanding of the "no"

"minor"

"laterality"and "serious"between previous scale scores and evaluating-diversities scores（P<0.05）.These differences are also obvious in each parted scales.Evaluating-diversities clearly deviate from normal to right distribution.There is high frequency of 0 value.Conclusion There are significant difference betueen the two calculational methods in each parted scales of the first 45 questions in SCL-90.There is minor difference betueen the two calculational methods.Therefore there are continuity and vagueness in measurement of scores and there is deficiency in previous scale scores.