Continuous renal replacement therapy (CRRT) is especially suitable for critically ill patients with unstable clinical conditions among the various extracorporeal blood purification therapies. CRRT enables continuous and slow removal of water and solutes and improvement of metabolic imbalances, and at the same time, stabilizing hemodynamics and facilitating the restoration of kidney function. The selection and optimal combination of replacement fluids based on patient conditions and treatment goals play a pivotal role in the safe and effective performance of CRRT. In the past, the type and quality of replacement fluids proposed in the clinical guidelines, expert consensus and operational protocols from China and foreign countries have been recommended. However, these recommendations are quite different from the preparation and supply of replacement fluids currently used in clinical practice. The establishment of a standardized and practical classification of replacement fluids are required for clinically rational application of replacement fluids and for healthcare professionals to develop effective fluid management and anticoagulation strategies. Based on the three rules, i.e., featuring the present situation of clinical practice, enabling quick clinical decision-making, and reflecting the future technology advances, the expert group of Zhongguancun Nephrology & Blood Purification Innovation Alliance (NBPIA) proposed an expert consensus on the classification of clinical application of replacement fluids for CRRT. This consensus combines clinical evidences and practical experiences, suggests the classification method for replacement fluids according to preparation method, base composition and mixing method, and recommends the classification system and clinical use of replacement fluids for CRRT, in order to improve the clinical use of replacement fluids, the quality evaluation, the standardized management, and the overall quality of CRRT in China.