Objective: A double-blind and double-simulated study was used to evaluate the effects of cognitive functioning in schizophrenics receiving different antipsychotic medications. Method: Forty Patients with schizophrenia were randomly divided into quetiapine group (n=20) and chlorpromazine group (n=20). Neuropsychologiacal tests were done before treatment and in the fourth and sixth week after therapy, which included knowledge, arithmetic, digital sign, digital span, game of puzzle, logical memory visual reproduction,STROOP test, verbal fluency, score and plan time of tower of Hanoi and WCST. Twelve healthy individuals were tested in same time to study the learning effects. Double-blind and a double-simulated means was adopted in this study. Results: Marked improvement was found in patients after quetiapine treatment. While chlorpromazine do not appear to favorably affect on cognitive functioning in schizophrenics. Scores of improvement on some neuropsychological assessment of quetiapine group were higher than that of chlorpromazine group, especially in attention and executive function(P