Introduction: Nursing in the oncology ward is associated with various stressors that can affect the psychological status of nurses. This study aimed to determine the effect of positive thinking skills training on the happiness and resilience of nurses in oncology center in shahid baqaei two hospitals of Ahvaz. Methods: This quasi-experimental interventional study was performed in 2021. 64 nurses working in five oncology wards of Baqaei two Hospitals in Ahvaz were selected by the available sampling method and entered the study. Research tools included a demographic questionnaire, Oxford Happiness Questionnaire, Connor Resilience, and Davidson CD-RIS. For the experimental group, the intervention including optimism and positive thinking skills training (Martin Seligman 1988) was performed in 8 sessions of 45 minutes and a retest was performed one week after the intervention. Results: There were no statistically significant differences between the two groups in terms of age groups, gender, education level, marital status, employment status, work experience, and shift work in the test and control groups (P<0. 05). The paired t-test showed that there was a significant difference in the resilience score of the test group before and after the intervention (P < 0. 001), while there was no significant difference in the control group (P = 0. 053). The independent t-test showed that the two groups did not have a significant difference in terms of resilience before the intervention (P = 0. 094), while after the intervention, this difference was significant (P < 0. 001). Also, the paired t-test showed that the happiness score of the test group before and after the intervention had a significant difference (P<0. 001), and there was also a significant difference in the control group (P = 0. 028). The independent t-test showed that the two groups had a significant difference in terms of the variable of happiness before (P = 0. 016) and after the intervention (P < 0. 001). Conclusions: The results of this study showed that the level of happiness and resilience of nurses is enhanced by teaching positive thinking skills. Positive Thinking Skills Training is an uncomplicated, low-cost, and practicable approach that has been proven to be effective in this study and can therefore be widely used as an empowerment program for nursing staff, especially in oncology wards.