Objective To develop the Caregiving Ability Assessment Scale for Primary Caregivers of Infants with Congenital Heart Disease Post-Operatively，to test its reliability and validity， and to provide a valid tool to assess the caregiving ability of primary caregivers of these infants. Methods Based on the Caregiver Care Ability-Effect model, combined with the literature review method and semi-structured interview results, the scale dimensions and item pool were preliminarily constructed, and the initial scale was formed through the expert group meeting method and pre-survey. Convenience sampling was used to select 360 primary caregivers of postoperative infants with congenital heart disease for questionnaire survey. Reliability and validity testing of the scale was performed with the survey data. Results The final version of the scale included 4 dimensions of care knowledge, care skills, personal quality of caregivers, management of family and social resources, totaling 29 items. Exploratory factor analysis extracted 4 common factors, and the cumulative variance contribution rate was 74.604%. The average content validity index (CVI) of the scale was 0.982, the item-level CVI ranged between 0.900-1.000; the overall Cronbach′s α coefficient of the scale was 0.956, the overall Omega reliability of the scale was 0.949, the split-half reliability was 0.846, and the retest reliability after 2 weeks was 0.873. The results of confirmatory factor analysis showed that the model was fitted. The combined reliability coefficient of the four dimensions of the scale ranged between 0.901-0.964, the convergent validity index AVE ranged between 0.651-0.756, and the square root of AVE of each dimension was 0.807-0.869. Conclusion The Caregiving Ability Assessment Scale for Primary Caregivers of Infants with Congenital Heart Disease Post-Operatively is reliable and effective. It can be used to evaluate the caregiving ability of primary caregivers of postoperative infants with congenital heart disease.