Eighty chronic schizophrenia inpatients who received conventional antipsychotics for more than one year, and met Schooler and Kane's criteria for persistent TD were enrolled in the study. The subjects were randomized to three groups: the olanzapine, amisulpride and FGA (first generation antipsychotic) controlled groups. Neurocognitive function were assessed using Wisconsin Card Sorting Test (WSCT) and Continuous Performance test (CPT) at baseline, 12th week and 24th week. Clinical successive ratings were performed with Brief psychiatric Rating Scale (BPRS), AIMS (Abnormal Involuntary Movement Rating Scale), Simpson-Angus Rating Scale (SAS), Udvalg for Kliniske Undersogelser side effect ratings (UKU) and Barnes akathesia scale (BAS).To evaluate the influences of prognostic factors on tardive dyskinesia and neurocognitive function and to control for all potential confounding variables, longitudinal analyses on the repeated measures data were conducted using generalized estimating equation models (GEE).