Introduction: The aim of this study was to compare the changes in serum concentrations of vascular endothelial growth factor (VEGF)-A and B after intravitreal injection of ranibizumab (IVR) or conbercept (IVC) for retinopathy of prematurity (ROP). Methods: In this prospective study, infants with type 1 ROP in both eyes were recruited in our hospital from September 2021 to February 2022, randomly assigned to the ranibizumab and conbercept groups and administered IVR or IVC (0.25 mg/0.025 mL). Blood samples were collected before the operation and 1 and 4 weeks after the operation to measure the concentrations of serum VEGF-A and B. Results: A total of 20 ROP infants were randomly assigned to the ranibizumab (n = 10) and conbercept groups (n = 10). In the ranibizumab group, the serum VEGF-A concentrations before operation and 1 and 4 weeks after the operation were 73.55 ± 40.78, 11.47 ± 7.00, and 75.36 ± 30.87 pg/mL, respectively (p < 0.01). Least Significant Difference (LSD) pairwise comparison did not show any significant difference in the groups between 4 weeks postoperatively and preoperatively (p > 0.05). In the conbercept group, the serum VEGF-A concentrations before operation and 1 and 4 weeks after the operation were 86.69 ± 55.06, 14.68 ± 10.11, and 43.55 ± 57.92 pg/mL, respectively (p < 0.01). LSD comparison showed significant differences between 1 week and 4 weeks postoperatively and preoperatively (p < 0.05), but no significant differences were observed between 1 and 4 weeks postoperatively (p > 0.05). Regarding serum VEGF-B concentrations before the operation and 1 and 4 weeks after the operation, no significant differences were detected in the ranibizumab group (p > 0.05), but significant differences were observed in the conbercept group (7.26 ± 2.34, 3.09 ± 2.41, and 4.55 ± 3.37 ng/mL, respectively; p < 0.01). LSD showed significant differences between 1 or 4 weeks postoperatively and preoperatively (p < 0.05), but no significant difference was detected between 1 and 4 weeks postoperatively (p > 0.05). Conclusions: Serum VEGF-A levels in infants with ROP were suppressed after IVR or IVC but returned to preoperative levels at 4 weeks after IVR and remained lower than the preoperative levels at 4 weeks after IVC. Serum VEGF-B was not affected by IVR but was suppressed by IVC for 4 weeks.