Objective To examine the effects of olanzapine and risperidone on cognitive function in treating schizophrenia. Methods Sixty two schizophrenics were assigned to receive olanzapine or risperidone treatment. The Positive and Negative Syndrome Scale （PANSS） ,Treatment Emergent Symptoms Scale （TESS） ,WAIS-Ⅲ Digit Span, Number sign,TMT--A,TMT--B and MMSE were used to measure therapeutic efficacy,side effects and cognitive function. Results The PANSS scores decreased significantly at 12 weeks after olanzapine or risperidone treatment （P〈0.05）, but no significant difference was found between two groups. The WAIS--III Digit Span, Number sign, the time ofTMT--A and TMT--13 and MMSE scores increased significantly after olanzapine or risperidone treatment. The right number of TMT--A score increased significantly only after olanzapine treatment. There were significant different in WAIS-Ⅲ Digit Span and the right number of TMT--B scores between two groups at the end of 12 weeks. The incidence rate of extrapyramidal symptoms was lower in oIanzapine group than in risperidone group （P 〈 0.05）. Conclusions Both olanzapine and risperidone were effective for schizophrenics and can improve cognitive function.