Continous renal replacement therapy(CRRT) is becoming increasingly popular for the support of critically ill patients with acute renal failure, and the development of pump-driven volumetric-control CRRT machines with small extracorporeal volumes has lead to the widespread use of venovenous form of CRRT in pediatric field. Basic principles are diffusion and convection. CRRT is indicated in the hemodynamically unstable pediatric patients for hypervolemic anuric acute renal failure, electrolyte abnormalities, multiorgan failure, catabolic patients with increased nutritional needs and hyperammonemia, etc. To date, experiences are limited for pediatric CRRT, but current reports support that CRRT is feasible and useful in children and even infants, and the survival rate of the patients on CRRT is as same as adults. We describe the basic principles, equipments, methods and complications of CRRT, with special considerations on small children to meet the current need for CRRT.