Objective  To investigate the effect of flexible ureteroscopic holmium laser lithotripsy (FURL) on unilateral upper urinary calculi and its influence on T lymphocyte subsets, renal function and oxidative stress factors in peripheral blood.Methods  From August 2017 to May 2019，100 patients with upper urinary tract stones admitted to our urology department were selected.Random number table method was used to divide the patients into control group and observation group,50 cases with each group.The control group was treated with percutaneous nephrolithotomy,while the observation group was treated with flexible ureteroscopic holmium laser lithotripsy.The operation time,hospitalization time, stone clearance rate, renal function,oxidative stress factor and T lymphocyte subsets were compared between the two groups 24 hours after operation.Results  The hospitalization time of the observation group was less than that of the control group, and the operation time and stone clearance rate were longer than or higher than those of the control group(P<0.05).There was no significant difference in BUN,Scr,β2-MG,HO-1,ET-1,COR,Ang-II,CD3⁺、CD4⁺、CD8⁺、CD4⁺/CD8⁺ between the two groups before operation(P>0.05).Twentyfour hours after operation,BUN,Scr,β2-MG,HO-1,ET-1,COR and Ang-II in the observation group increased less than those in the control group,while,CD3⁺、CD4⁺、CD8⁺、CD4⁺/CD8⁺levels increased, and CD8⁺ levels decreased more than those in the control group(P<0.05).The total incidence of operative complications in the observation group was 6.00% lower than that in the control group 22.00%(P<0.05).Conclusions   FURL has the advantages of high success rate, fewer complications,quick recovery,short hospitalization time,low oxidative stress response,low inhibitory effect on peripheral blood cell immune function,remarkable clinical efficacy and high safety.It is worthy of clinical promotion and application.