This meta-analysis aimed to evaluate the impact of aerobic exercise on Peak VO2 (Oxygen Consumption) in postoperative patients with congenital heart disease (CHD). Besides this, we also tried to discover whether the improvement was influenced by patient ages, modes of supervision, types of exercise, the total dose of exercise, intervention periods, and types of CHD. Following the Population Intervention Comparison Outcome Study Design (PICOS) principle, a comprehensive search of the PubMed, Web of Science, Embase and Cochrane Library databases was conducted for randomized controlled trials (RCTs) evaluating the intervention effects of aerobic exercise on cardiopulmonary function in postoperative CHD patients until December 2023. This meta-analysis and publication bias tests were conducted using Stata 17.0, and the mean differences (MDs) with 95% confidence intervals (CIs) were used as effect sizes in statistics. A total of 15 RCTs (762 cases) were included in this meta-analysis, with 407 cases in the experimental group and 355 cases in the control group. Meta-analysis showed that aerobic exercise had a positive effect on Peak VO2 in postoperative CHD patients (MD = 2.14, 95% CI (1.34, 2.94), p 0.00001, I2 = 36%). The analysis of subgroups showed that intervention effects of aerobic exercise were superior to the control group when patients were 18 years old (MD = 2.53, p 0.00001), 18 years old (MD = 1.63, p = 0.01), under supervision (MD = 2.23, p 0.00001), unsupervised (MD = 2.06, p 0.00400), performing aerobic exercise (MD = 1.87, p = 0.0003), performing aerobic exercise combined with resistance training (MD = 2.57, p 0.00010), with a total dose of exercise 1440 minutes (MD = 2.45, p 0.00010), with the intervention period of 10-12 weeks (MD = 2.31, p 0.00001), with that 12 weeks (MD = 1.97, p = 0.00300), or with mixed types of CHD (MD = 2.34, p 0.00001). This meta-analysis did not deduct points for limitations, inconsistency, indirectness, imprecision, or publication bias, so the quality of evidence was graded as high. Aerobic exercise has a significantly positive impact on improving Peak VO2 in postoperative CHD patients. Moreover, it was found that for patients aged 18 and above, supervised aerobic exercise combined with resistance training, implemented for 10-12 weeks with a total dose of exercise 1440 minutes, had a better intervention effect on Peak VO2. This finding provided evidence-based medicine for the exercise rehabilitation of postoperative CHD patients, and explored the optimal exercise prescription for clinical practice as well. Registered on INPLASY No.202440016 (https://inplasy.com).