Hemofiltration and hemodialysis are both blood purification methods, and the principle is to remove blood toxins and water through semi-permeable membranes, the difference between the two is as follows: 1. Hemofiltration: toxins and water are discharged through the principle of filtration, toxins are discharged from the blood in equal concentration, and then the replacement fluid is replenished before or after the filter. The pore size of the semi-permeable membrane of the dialyzer used for hemofiltration will be larger, and the discharge of medium-molecular toxins, i.e., toxins with a molecular weight of 5000-10000 Da, will be relatively large. Because toxins are discharged in equal concentrations, the efficiency of discharging small molecule toxins, like creatinine and urea nitrogen, is relatively low. 2. Hemodialysis:. Using the principle of diffusion to discharge toxins, the concentration of toxins in the blood is high, there is no toxin in the dialysis fluid, and small molecule toxins run from the blood to the dialysis fluid by diffusion. Hemodialysis semi-permeable membrane pore size is relatively small, which is more efficient for small molecule toxin discharge, but less for larger molecular weight such as 5000Da or above toxin discharge. So the two combined with each other, preferably three times a week hemodialysis, including two hemodialysis and one hemofiltration, will be more effective.