Rice-derived recombinant human serum albumin (OsrHSA) possesses an identical primary, secondary, and higher-order structure to plasma-derived human albumin. Through innovative production technology, it fundamentally circumvents the supply limitations and viral contamination risks associated with plasma sources, offering a novel solution to address clinical unmet needs. Existing research data have demonstrated that its efficacy and safety are non-inferior to plasma-derived human albumin in patients with cirrhosis complicated by hypoalbuminemia. However, no study has yet explored the safety and efficacy of OsrHSA in patients with postoperative hypoalbuminemia following hepatectomy. This study is a prospective, single-arm, small-sample, exploratory clinical trial aimed at evaluating the efficacy and safety of recombinant human serum albumin injection (rice) (OsrHSA) in patients with hypoalbuminemia after hepatectomy. All trial participants will receive daily intravenous infusion of 20 g OsrHSA (20%, 50 mL) starting from the day when postoperative hypoalbuminemia (\<30 g/L) is identified, with concurrent monitoring of serum albumin levels. The primary endpoints are the percentage of trial participants achieving serum albumin ≥35 g/L within one week, and the incidence of adverse drug reactions.