Background: Corrected QT (QTc) interval prolongation is one of the common causes of sudden cardiac death in patients with maintenance hemodialysis (MHD) patients. However, there are few studies on QTc prolongation in MHD patients. The concentration of lactate dehydrogenase (LDH) in hemodialysis population increased, and LDH was associated with the mortality of MHD patients. This study aimed to investigate the relationship between QTc interval prolongation and LDH in MHD patients. Methods: This is a cross-sectional observational study. Patients who underwent MHD for more than 3 months in the Second Affiliated Hospital of Nantong University from November 2012 to November 2019 with complete data were selected as the research subjects. The patients were divided into the normal QTc interval group and the QTc interval prolongation group. The general data of patients and clinical laboratory indicators were collected retrospectively from the electronic medical record system. Pearson correlation analysis and binary logistic regression were used to analyze the correlation between LDH and QTc interval prolongation; the cut-off value of LDH predicting QTc interval prolongation was calculated by receiver operating characteristic (ROC) curve;Results: The LDH level in the prolonged QTc interval group was significantly higher than that in the normal group (301.96±110.91 vs. 215.39±67.65, t=−8.03, P<0.001). QTc interval and LDH (r=0.386) were positively correlated. Binary logistic regression analysis showed that LDH, serum potassium <4 mmol/L, serum phosphorus, and left ventricular end-diastolic diameter (LVDd) were independent related factors for QTc interval prolongation. The ROC curve results showed that LDH =220 U/L was the best cutoff point for predicting QTc interval prolongation in MHD patients, with a sensitivity of 81.45% and a specificity of 59.35%. Binary logistic regression analysis showed that the LDH >220 U/L group was 6.34 times more likely to have QTc interval prolongation than the LDH ≤220 U/L group (OR 6.34, 95% CI: 3.47-11.58, P<0.001). Conclusions: LDH in MHD patients is closely related to QTc interval prolongation. Serum LDH, ionic calcium, serum phosphorus and potassium may predict QTc interval prolongation. Monitoring related indicators can remind clinicians to intervene as soon as possible to reduce the potential risk of arrhythmia and sudden cardiac death (SCD).