Objective To determine the influence of peroxisome proliferator-activated receptor (PPAR)-β/δ agonist, GW501516 (GW), on the cardiac function in aged septic rats. Methods The aged rat model of sepsis was established by cecal ligation and puncture surgery (CLP). Totally 50 aged rats (24 months old) were randomly divided into 4 groups: control group (Con, n＝5), sham operation group (Sham, n＝6), CLP group (n＝19), CLP+GW501516 (0.05mg/100g) group (n＝20). The mortality of the aged rats was recorded within 48 h after the CLP surgery. In 48h after CLP, the heart rate, stroke volume (SV), cardiac index (CI), left ventricular end-diastolic diameter and left ventricular end-diastolic volume were evaluated by echocardiography. Results CLP+GW group had significantly reduced mortality compared with CLP group (15.0% vs 42.1%, P＜0.05). The echocardiographic results showed that GW501516 resulted in greatly declined heart rate [(318.55±16.65) vs (411.16±10.1) beats/min, P＜0.01], and extremely increased SV and CI in 48h after surgery [(470.71±111.6) vs (171.47±39.85)ml/beat, P＜0.05; (185.00±41.2) vs (102.05±19.94)ml/(min·mm-2), P＜0.05] when compared with simple CLP operation. Left ventricular end-diastolic diameter and left ventricular end-diastolic volume were also significantly improved in CLP+GW501516 group compared with CLP group[(8.02±0.66) vs (5.65±0.45)mm, P＜0.05; (5.13±1.00) vs (1.75±0.39)ml, P＜0.01]. Conclusion Early application of PPARβ/δ agonist GW501516 reduces the mortality and improves cardiac systolic and diastolic function in aged septic rats.