We aimed to evaluate the relationship between post-stent fractional flow reserve (FFR) and intravascular ultrasound (IVUS) parameters for stent optimization. IVUS and FFR measurements were performed in 101 coronary lesions after successful percutaneous coronary intervention (PCI). Quantitative IVUS parameters for stent optimization such as minimal intra-stent cross sectional area (CSA), proximal, and distal reference lumen CSA, and plaque burden (PB) at both edges of the stent related to the post-stent FFR. Mean post-stent FFR was 0.91 ± 0.06. Post-stent FFR ≤ 0.90 was observed in 46 (45.5%) lesions. The 55 lesions with post-stent FFR > 0.9 had larger proximal CSA (9.2 ± 2.9 mm² vs. 7.4 ± 2.3 mm², p = 0.001), distal reference lumen CSA (7.4 ± 2.7 mm² vs. 6.3 ± 2.1 mm², p = 0.017), minimum intra-stent lumen CSA (7.4 ± 2.5 mm² vs. 6.1 ± 1.7 mm², p = 0.004), and lower proximal reference PB (45 ± 8.2% vs. 50 ± 11%, p = 0.017) than did those with post-stent FFR ≤ 0.90. Post-stent FFR had an inverse correlation with age, left anterior descending artery (LAD) against non-LAD, and proximal reference PB and a positive correlation with pre-stent FFR, proximal and distal reference lumen CSA, and minimum intra-stent lumen CSA. Meanwhile, no correlation was found between post-stent FFR and stent length. Pre-stent FFR (β = 0.544), proximal reference lumen CSA (β = 0.530) and age (β = − 0.251) were found to be independently associated with the post-stent FFR. Post-procedural FFR might partly reflect the appropriateness of PCI results in terms of the adequate expansion of the stent and full lesion coverage on IVUS.