Objective:To study the safety and efficacy on timing of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) stageⅡbased on increase in remnant liver volume.Methods:19 patients (male: female 13: 6; average age 53 years) with liver tumors treated by ALPPS from April 2014 to December 2020 were retrospectively studied. Patients with FLV/ESLV (future liver volume/ estimated standard liver volume) increase of more than 50% within 1 week followed by stageⅡALPPS were included into the rapid group ( n=8). Those who failed to have 50% increase in FLV/ESLV within 1 week were included into the control group ( n=11). The two groups were compared in the ALPPS stage II in operating time, blood loss, postoperative complications, mortality rate and hospital stay. Results:All 19 patients underwent ALPPS stage II uneventfully. One patient in the control group died from liver failure within 30 days of operation. The operation time (3.2±1.8)h, blood loss (554±227) ml and postoperative hospital stay (12.6±2.4) d in the rapid group were significantly better than those in the control group (4.7±2.2) h, [(760±314) ml, (18.2±6.4) d (all P<0.05)]. The two groups had similar complication rates in both post stageⅠ[37.5%(3/8) vs. 45.4%(5/11)] , or stageⅡ [37.5%(3/8) vs. 36.4%(4/11)] (both P>0.05). Conclusion:Rapid increase in FLR volume of more than 50% within a week was safe and feasible to proceed to ALPPS stage II. This conclusion needs to be confirmed by further studies using large sample sizes.