Schizophrenia is the most severe chronic disabling psychiatric disorder that needs long term care in various aspects. Therefore, the family's emotional atmosphere caused by the disease affects the condition of the patients' caregivers. This study aimed to investigate the effect of emotional regulation training on stress, anxiety, and depression in caregivers of patients with schizophrenia. The study was a randomized controlled trial. Seventy caregivers of patients with schizophrenia randomly assigned to a group that received emotion regulation training and a control group. The intervention group was trained about emotion regulation during eight 90-min sessions. The participants completed the Depression, Anxiety and Stress Scales-21 questionnaire before and one month after the intervention. The results showed that stress, anxiety and depression scores significantly reduced in the intervention group compared to the control group. Emotional regulation training with cognitive methods has significantly reduced the anxiety, stress, and depression of caregivers of patients with schizophrenia.