Background: It has not been solved what kind of needle sensation might influence outcomes of acupuncture treatment. Effects of personality factors on the therapeutic effect of acupuncture have not been investigated. This study aimed to find the effects of the traits of personality on the objective outcome when different acupuncture techniques were used in treating patients with Bell's palsy. Methods: We performed a secondary analysis of a prospective multicenter randomized controlled trial of acupuncture for Bell's palsy. Patients were randomly assigned to the de qi and control groups, respectively. The primary outcome was facial nerve function at month 6. The intensity of each needle sensation was rated by a visual analog scale. Psychosocial factors were assessed by the pretreatment mediator questionnaire; 16 Personality Factor Questionnaire (16PF) was used for assessing personality factors and digit cancellation test for assessing attention. Results: After 6 months, patients in the de qi group had better facial function (adjusted odds ratio [OR]: 4.16, 95% confidence interval [CI]: 2.23u7.78). Path analysis showed that intensity of needle sensation of fullness had direct effect on House-Brackmann (HB) score at month 6. In de qi group, the low HB score on day 1 (OR: 0.13, 95% CI: 0.03u0.45) and the low Social Boldness score (OR: 0.63, 95% CI: 0.41u0.97) in 16PF were associated with better facial function. In control group, low HB score on day 1 (OR: 0.25, 95% CI: 0.13u0.50), low Vigilance score (OR: 0.66, 95% CI: 0.50u0.88), and high Tension score (OR: 1.41, 95% CI: 1.12u1.77) in 16PF were related to better facial function. Conclusions: The needle sensation of fullness could predict better facial function and personality traits might influence outcomes of acupuncture treatment. Both of them should be considered seriously in acupuncture treatment and research.