Generalized anxiety disorder (GAD) has harmful effects on physical and mental health and quality of life. Coloring therapy has been reported to have a positive effect on improving patient anxiety and depression. But there are no reported clinical trials examining their effectiveness as a treatment for GAD. This study was planned to evaluate the effectiveness of coloring therapy combined with conventional therapy in improving anxiety, depression, and positive and negative emotions with GAD. This randomized controlled study comprising 88 GAD patients was selected for intervention in different wards. The control group (n = 45) was given conventional antianxiety medication and physical therapy, and the experimental group (n = 43) received coloring therapy combined with conventional therapy. The Self-Rating Depression Scale, Self-Rating Anxiety Scale (SAS), Hamilton Depression Scale, Hamilton Anxiety Scale (HAMA), and Positive and Negative Affect Scale were assessed in both groups before and 3 weeks after the intervention. After the intervention, there were statistical differences in intra-and inter-group comparisons of anxiety, depression, and positive and negative mood scales in the experimental and control groups (p < .05). The minus in anxiety/positive emotions pre-and postintervention in the experimental group was statistically significant compared to that in anxiety/positive emotions pre-and postintervention in the control group (HAMA: d = 1.45, 95% confidence interval [CI] (0.34, 2.57), p = .011; SAS: d = 3.87, 95% CI (1.73,6.00), p = .001; positive: d = 1.76, 95% CI (0.17, 3.34), p = .030). The minus in depressive/negative emotions pre-and postintervention in the experimental group was not statistically significant compared with that in depressive/negative emotions pre-and postintervention in the control group (p > .05). For GAD patients, adding coloring therapy based on conventional drug therapy and physical therapy can not only reduce depression and negative emotions but also have better effects on reducing anxiety and improving positive emotions than conventional therapy.