Background Lower low-density lipoprotein cholesterol (LDL-C) is significantly associated with improved prognosis in patients with coronary artery disease (CAD). However, LDL-C reduction does not decrease all-cause mortality among CAD patients when renal function impairs. There are currently no studies examining the association of low baseline LDL-C concentration (<1.8 mmol/L) with mortality among patients with CAD and advanced kidney disease (AKD). We aimed to evaluate prognostic value of low baseline LDL-C level for all-cause death in these patients. Methods In this observational study, 803 CAD patients complicated with AKD (eGFR <30 mL/min/1.73 m 2) were enrolled between January 2008 to December 2018. Patients were divided into two groups (LDL-C <1.8 mmol/L, n=138; LDL-C ≥1.8 mmol/L, n=665). We used Kaplan-Meier methods and Cox regression analyses to assess the association between baseline low LDL-C levels and long-term all-cause mortality. Results Among 803 participants (mean age 67.4 years; 68.5% male), there were 315 incidents of all-cause death during a median follow-up of 2.7 years. Kaplan–Meier analysis showed that low LDL-C levels were associated with worse prognosis. After adjusting for full 24 confounders (e.g., age, diabetes, heart failure, and dialysis, etc.), multivariate Cox regression analysis revealed that lower LDL-C level (<1.8mmol/L) was significantly associated with higher risk of all-cause death (adjusted HR, 1.38; 95% CI, 1.01–1.89). Conclusions Our data demonstrated that among patients with CAD and AKD, a lower baseline LDLC level (<1.8mmol/L) did not present a higher survival rate but was related to a worse prognosis, suggesting a cautiousness of too low LDL-C levels among patients with CAD and AKD. FUNDunding Acknowledgement Type of funding sources: Foundation. Main funding source(s): This study was supported by the National Natural Science Foundation of China (Grant No. 81670339 and Grant No. 81970311), Cardiovascular Research Foundation Project of the Chinese Medical Doctor Association (SCRFCMDA201216) and Beijing Lisheng Cardiovascular Health Foundation (LHJJ20141751).