Objective To understand the core competencies of obstetrics and gynecology residents undergoing standardized residency training in Guizhou Province (referred to as residency training), and to inform quality improvement of residency training. Methods The method of questionnaire survey was adopted. From April to June 2022, a self-assessment survey was conducted on the core competence of 322 trainees from 17 residency training bases of obstetrics and gynecology in Guizhou Province in six aspects: professional literacy, professional competence, patient management, communication and cooperation, teaching ability and learning improvement. One-way ANOVA analysis of variance and t-test were used to analyze the relevant data. Results The core competency self-score of trainees was (4.09±0.62) points. Among the 6 core competency, the scores from high to low were: professional literacy [(4.27±0.65) points], communication and cooperation [(4.18±0.64) points], patient management [(4.09±0.65) points], professional competence [(4.07±0.65) points], teaching ability [(3.99±0.68) points], learning and improvement [(3.88±0.71) points]. The total core competency score [(4.24±0.57) points] of the trainees who could fully implement the training plan was higher than that of the majority of the trainees who could [(3.97±0.57) points], basically could [(3.86±0.71) points], and could not [(3.57±0.63) points] implement the training plan. The total core competency scores of the trainees who were very willing to engage in medical profession [(4.17±0.60) points] were higher than those who were unwilling to engage in medical profession [(3.76±0.63) points], all P<0.05. Conclusions The core competencies of residents in the six aspects have not been balanced and need to be improved. In future training, attention should be paid to the cultivation of core competencies such as teaching ability and learning improvement of residents, and the training plan of residents should be strictly implemented to improve their willingness to work.