Butylphthalide (NBP) is a neuroprotective medication capable of ameliorating neurological dysfunction induced by ischemia, hypoxia, and reperfusion injury in the brain. However, evidence regarding the improvement of neurological function prognosis in patients with return of spontaneous circulation (ROSC) after cardiac arrest (CA) by NBP is limited. This study aims to evaluate the safety and efficacy of NBP treatment in improving the neurological function prognosis of patients with ROSC after CA.The study will be a single-center, randomized, double-blind, placebo-controlled trial. The sample size is estimated to be 100 patients. Eligible patients will be randomly allocated in a 1:1 ratio to receive either NBP or placebo treatment daily for a duration of 14 days. The initial administration of NBP or placebo treatment will commence within 6 hours after ROSC following CA. The primary outcome is the proportion of patients with Cerebral Performance Category (CPC) scores of 1-2 at 90 days after randomization in each group. The primary safety outcome is the percentage of severe adverse events occurring during the 14-day treatment period. This trial will determine the efficacy of NBP in providing neuroprotective effects for patients with ROSC after CA.