Objective To explore the mediating effects of personal resourcefulness and adversity appraisal between post competency and public health emergency (PHE) response ability among critical care nurses. Methods A total of 430 critical care nurses were selected as the research subjects using the convenience sampling method. The questionnaire survey was conducted using ICU Nurse Core Competency Scale, Resourcefulness Scale, Adversity Appraisal Scale, and Public Health Emergency Response Ability Questionnaire for Nurses. The structural equation model and the Bootstrap method was used to test the chain mediating effect of personal resourcefulness and adversity appraisal between post competency and the ability to respond to PHE. Results The scores of post competency, personal resourcefulness, adversity appraisal and PHE response ability were (67.5±13.3), (90.7±14.5), (44.2±7.9) and (62.4±8.0), respectively. The post competency score was positively correlated with personal resourcefulness, adversity appraisal and PHE response ability [correlation coefficient (r) was 0.763, 0.685 and 0.720, all P<0.01]. The personal resourcefulness score was positively correlated with adversity appraisal and PHE response ability (r was 0.629 and 0.716, all P<0.01). The adversity appraisal score was positively correlated with PHE response ability (r was 0.707, P<0.01). The total effect of post competency on PHE response ability was 0.551. Personal resourcefulness and adversity appraisal played a partial mediating role in the effect of post competency on PHE response ability, and the mediating effect accounted for 27.2% and 18.0% respectively. Their combined chain mediating effect accounted for 17.2% of the total effect. Conclusion Post competency not only directly predicts PHE response ability but also indirectly influences it through the chain mediation of personal resourcefulness and adversity appraisal in critical care nurses.