Chronic kidney disease (CKD) is a global public health problem. In 2002, National Kidney Foundation (NKF)’s Kidney Disease Outcomes Quality Initiative (K/DOQI) published a guideline, which introduced a definition and classification system for CKD. This guideline plays an important role in the diagnosis, treatment and prognosis improvement for CKD. However, lots of evidence from clinical and epidemiological trials caused plenty of debates and controversies towards the applicability of present K/DOQI-CKD definition and classification system. These problems included high prevalence of CKD, disproportionately high prevalence in CKD stage 3, and high prevalence of CKD in the elderly. What’s more, whether patients with simple renal cyst should be diagnosed as CKD or not have not reached a consensus yet. So Kidney Disease: Improving Global Outcomes (KDIGO) published another guideline in 2012. The new one revised the definition of CKD, established a combined staging system concerning causes, glomerular filtration rate (GFR) and albuminuria, made a risk stratified model to estimate prognosis, and recommended the application of CKD-EPI to estimate GFR.