Pneumonia is characterized by high incidence and mortality rates in elderly patients (≥65 years old). Piperacillin-tazobactam, as a broad-spectrum antibiotic, has its therapeutic efficacy and safety potentially influenced by the infusion regimen. However, research on infusion regimens specifically targeting the elderly population is currently limited. In our preliminary dose simulation, under the pharmacokinetic/pharmacodynamic (PK/PD) target of achieving a free drug concentration time percentage above 100% of the minimum inhibitory concentration (fT%\>100% MIC), the regimen of administering the drug every 6 hours (q6h) achieved a concentration compliance rate of 90% within 4 hours. This study aims to explore the differences between two infusion modes (q6h for 4 hours vs. q8h for 3 hours) and to provide preliminary evidence for clinical practice.