In our study, 600 patients with SAKI at KDIGO 2 from multicenter in China will be recruited. And then the patients will be divided into early group and delayed group randomly. In the early group, CRRT was started immediately after randomization. In the delay group, CRRT was initiated if at least one of the following criteria was met: KDIGO 3, severe hyperkalemia, metabolic acidosis, pulmonary edema, blood urea nitrogen level higher than 112 mg per deciliter, or oliguria for more than 72 hours after randomization. Overall survival at day 90 will be observed in order to understand whether different CRRT strategy would affect the outcomes of SAKI.