Six varieties of Erianthus arundinaceus were assessed as potential energy crops and compared with switchgrass. Bioethanol and biomethane were produced as well. The chemical composition, elemental composition, and heating values were close to those of switchgrass except for a higher cellulose content. All varieties scored higher than 110, suggesting excellent potential as an energy crop. Pretreatment resulted in almost complete hydrolysis and achieved a higher glucose yield. In particular, E33 and E19 yielded 337.4 g and 332.4 g glucose, respectively, from 1.0 kg of feedstock compared with 312.1g/kg for switchgrass. E33, E49, and E19 exhibited a higher ethanol yield of 144.2 g/kg, 146.9 g/kg, and 149.6 g/kg feedstock, respectively, at a solids loading of 15%. No obvious influences could be observed on anaerobic digestion performances. A 16.3%, 14.6%, 14.0%, and 13.1% higher yield on cumulative methane could be obtained from E17, E23, E33, and E6, respectively, compared to switchgrass. Bioethanol and biomethane could be maximally obtained from E19 (6820 kg/ha) and E17 (3916 m3/ha), respectively. Thus, they are specially recommended for bioethanol and biomethane production, respectively. E33 can be suggested as a flexible variety for yielding relatively high bioethanol (6008 kg/ha) and biomethane (3409 m3/ha).