Background Insufficient blood supply in the gastric tube is considered as a risk factor for postoperative anastomotic strictures in patients receiving esophagectomy, but the direct evidence is lacking. Aims We aimed to investigate the correlation between perioperative blood supply in the anastomotic area of the gastric tube and the formation of anastomotic strictures in the patients undergoing esophagectomy. Methods This prospective study included 60 patients with esophageal squamous cell carcinoma undergoing Ivor Lewis esophagectomy between March 2014 and February 2016, which were divided into stricture group (n = 13) and non-stricture group (n = 47) based on their severity of anastomotic strictures at 3 months post-operation. The perioperative anastomotic blood supply was measured using a laser Doppler flowmetry. The gastric intramucosal pH (pHi) was measured by a gastric tonometer within 72 h post-operation. The perfusion index and gastric pHi were compared between groups. Results The stricture group had a significantly lower blood flow index (P < 0.001) and gastric pHi values from day 1 to day 3 post-operation than the non-stricture group (all P < 0.001). In addition, Pearson correlation analysis showed that both the perfusion index and gastric pHi were significantly correlated with stricture size and stricture scores, respectively (r = 0.65 - 0.32, all P < 0.05). Furthermore, the multivariate logistic regression analysis showed that perfusion index was an influential factor associated with postoperative anastomotic strictures (OR 0.84. 95% CI 0.72-0.98, P = 0.026). Conclusion These results suggested that poor blood supply in the anastomotic area of the gastric tube in the perioperative period was a risk factor for postoperative anastomotic strictures.