Background: As inadequate pain communication contributes to difficulties in optimizing outcomes of outpatients, we investigated the effect of reinforced education using WeChat App to the opioid titration treatment of cancerrelated pain in the outpatient setting. Methods: We conducted a prospective study to compare reinforced education using Wechat with care as usual from February to December 2019. Patients in the reinforced education group received reinforced education via Wechat, while those in the control group received care as usual. Effect measurements for both groups are carried out with questionnaires at the baseline and 3 days later. Questionnaires include pain intensity (NRS), treatmentrelated adverse events, cancer-related quality of life (QOL), sleep (PSQI), satisfaction, anxiety (GAD-7) and depression (PHQ-9). Number of patients whose NRS reduced to less than three points in 24 h was the primary outcomes. Secondary outcomes included treatment-related adverse events, cancer-related quality of life, sleep, satisfaction, anxiety and depression. Results: Although there was no significant difference regarding pain intensity (NRS) between the two groups at 72 h, the rate of NRS that reduced to less than three points in 24 h was significantly higher in the Wechat group than in the control group. Patients' satisfaction was significantly higher in the Wechat group than in the control group. There was no significant difference between the two groups regarding the other findings at 72 h, including pain intensity (NRS), cancer-related quality of life (QOL), anxiety (GAD-7), depression (PHQ-9), and sleep (PSQI). However, no significant difference was found between the two groups for constipation, nausea, vomiting, dizziness, somnolence, pruritus, loss of consciousness, and death.