This study aimed to compare olanzapine and haloperidol efficacies in the treatment of acute psychiatric symptoms due to amphetamine-type stimulants (ATSs). The Zelen II design method was used; 124 patients with acute mental disorders due to amphetamine were randomly divided into olanzapine group (n = 63) and haloperidol group (n = 61). Then, a 4-week open-label medical therapy was performed. Clinical Global Impression Scale Item 2 was employed to evaluate the onset time; meanwhile, Brief Psychiatric Rating Scale (BPRS) was used at baseline and at posttreatment weeks 1, 2, and 4. Moreover, adverse reactions during the treatment were recorded. Onset time in the olanzapine group was significantly earlier than in the haloperidol group; BPRS scores in the olanzapine group were significantly lower than haloperidol group values at 1 and 2 weeks of treatment. The overall effective rates had no statistically significant difference. Short-term olanzapine and haloperidol treatments had equivalent efficacies in the treatment of acute symptoms of mental disorders due to ATSs; however, olanzapine administration resulted in relatively earlier disease onset, with less adverse reactions.