Objective: To discuss the predictive effect of CT value of renal calculi on exible ureteroscopy with holmium laser lithotripsy. Methods: 133 cases of patients with single renal calculi performed by flexible ureteroscopy with holmium laser lithotripsy in our hospital were analyzed retrospectively, according to the measured mean CT value of calculus, the patients were divided into low-value group (CT value<800 HU, n=70) and the high-value group (CT value≥800 HU, n=63). The renal calculi removal rate, operation time and complications were compared between the two groups.Logistic multivariate regression analysis was used to investigate the influencing factors of flexible ureteroscopy with holmium laser lithotripsy removing single renal calculi. Results: There was no statistically significant difference between low-value group and high-value group in general data such as gender, age, calculi diameter, calculi site, and disease association (P>0.05). The calculi clearance rates of low-value group and high-value group were 92.86% and 76.19%, respectively. The difference between the two groups was statistically significant (P<0.05).The operative time was (83.23±12.71) min and (119.40±16.35) min, respectively. The difference between the two groups was statistically significant (P<0.05).The incidence of surgical complications was 4.29% and 17.46%, respectively, with statistically significant differences between the two groups (P<0.05).Logistic multivariate regression analysis showed that CT value and operation time of calculus were independent risk factors affecting calculi clearance rate. Conclusion: CT value of calculi has certain predictive value for lithotripsy time, calculi clearance rate of flexible ureteroscopy with holmium laser lithotripsy.