Abstract: Leniency effect in performance appraisal had great harmful influences on human resource management. In this paper, leniency effect was analyzed in three dimensions: situational factors, instrumental factors and rater factors. Organizational culture, purpose of appraisal and rater anonymity were regarded as situational factors. Standards of rating was discussed as instrumental factor especially. Motivation, cognitive process, affects, moods, and raters’ stabile personal traits were regarded as rater factors. At the same time, suggestions of how to cope with leniency effect were provided. Finally, some aspects that need to further research were proposed

Key words: performance appraisal, leniency effect, rater