Objective: To evaluate the therapeutic effect of cerebrospinal fluid (CSF) replacement in subarachnoid hemorrhage (SAH) and analyze the endpoint of replacement volume. Methods: 36 patients with spontaneous or traumatic SAH and intracerebral hemorrhage breaking into the subarachnoid space received by the hospital from August 2024 to April 2025 were selected. Different volumes of CSF were replaced with routine operation, and the clinical efficacy was analyzed. Results: All 36 patients were effective without any complications. In terms of replacement volume, the patients in the clear CSF replacement group had a greater decrease in VAS scores immediately and at 48 hours, and their symptom relief was more significant. The difference was statistically significant by t-test. Regarding the average frequency of CSF replacement, the control group had a higher average frequency than the clear group, but there was no statistical difference by the rank sum test. Conclusion: CSF replacement therapy can effectively improve clinical symptoms in patients with SAH. In terms of replacement volume, patients in the clear CSF replacement group had a greater decrease in VAS scores immediately and at 48 hours, with more significant symptom relief. Therefore, CSF replacement should be thorough, has high safety, and is worthy of clinical promotion.