Within the context of residual cardiovascular risk in post-statin era, emerging evidence from epidemiologic and human genetic studies have demonstratedthattriglyceride (TG)-rich lipoproteinsand their remnants are causally related to cardiovascular risk. While,carriers of loss-of-function mutations of ApoC3 havelow TG levelsand are protected from cardiovascular disease (CVD). Of translational significance,siRNAs/antisense oligonucleotide (ASO) targeting ApoC3 is beneficial for patients with atheroscleroticCVD. Therefore, animal models of atherosclerosiswith bothhypercholesterolemia and hypertriglyceridemia are important for the discovery of novel therapeutic strategies targeting TG-lowering on top of traditional cholesterol-lowering.In this study, we constructed a novel mouse model of familial combined hyperlipidemia through inserting a human ApoC3 transgene(hApoC3-Tg) into C57BL/6 J mice and injecting a gain-of-function variant of adeno-associated virus-proprotein convertase subtilisin/kexin type 9 (AAV-PCSK9)-D377Y concurrently with high cholesterol diet (HCD) feeding for 16 weeks. In the last 10 weeks, hApoC3-Tg mice were orally treated with a combination of atorvastatin (10 mg·kg-1·d-1) and fenofibrate (100 mg·kg-1·d-1). HCD-treated hApoC3-Tg mice demonstrated elevated levels of serum TG, total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C). Oral administration of atorvastatin and fenofibrate significantly decreased the plaque sizes of en face aorta, aortic sinus and innominate artery accompanied by improved lipid profileand distribution. In summary,this novel mouse model is of considerable clinical relevance for evaluation of anti-atherosclerotic drugsby targeting both hypercholesterolemia and hypertriglyceridemia.