【Objective】 To determine the risk factors of urinary sepsis secondary to minimally invasive percutaneous nephrolithotomy (mPCNL) in patients with negative preoperative urine culture (UC). 【Methods】 A total of 274 patients with negative preoperative UC treated with mPCNL during Jan.2016 and Jun. 2021 were retrospectively analyzed. The incidence of urinary sepsis was observed, and the general data of patients with or without urinary sepsis after mPCNL were compared. logistic regression model was used to analyze the risk factors of urinary sepsis after mPCNL. 【Results】 Urinary sepsis occurred in 11 cases (4.01%). Univariate analysis showed that urinary sepsis was associated with gender, body mass index, stone load, diabetes, urine WBC ≥2+, urinary nitrite, procalcitonin, and operation time. Multivariate logistic regression analysis showed that the independent risk factors of urinary sepsis after mPCNL included diabetes (OR=2.34, 95%CI=1.051-5.43, P=0.037), stone load (OR=7.51, 95%CI=3.17-7.38, P=0.045), urine WBC≥2+ (OR=4.57, 95%CI=6.75-11.38, P=0.032), urinary nitrite positive (OR=6.45, 95%CI=0.93-26.87, P=0.028) and operation time≥120 min (OR=3.53, 95%CI=1.41-8.85, P=0.042). 【Conclusion】 Diabetes, stone load, urinary WBC ≥2+, positive urinary nitrite and operation time ≥120 minutes are the risk factors of urinary sepsis after mPCNL in patients with negative urine culture.