Biocomposites, also referred to as green composites, have been increasingly received attentions in industries as well as in academia for the last decades. A large number of studies on biocomposite materials have been focusing on synthetic polymers as matrix and cellulose-based natural fibers such as kenaf, jute, flax, hemp, etc. as reinforcement. Recently, biodegradable polymers such as poly(butylene succinate) (PBS) and poly(lactic acid) (PLA) have been increasingly used as environmentally friendly polymer matrix for replacing some targeting synthetic polymer resins. Protein-based or animal-based natural fibers such as silk and wool may also be promising as potential reinforcement of biocomposites. In general, PBS has merits such as processibility, toughness, and high heat deflection temperature but it has poor mechanical properties. Hence, the property enhancement of PBS is often needed for extended applications. The most useful way to enhance the mechanical and/or thermal properties of biocomposites is reinforcing the PBS with natural fibers. Fundamentally, the properties and performances of a composite material significantly depend not only on the fiber/resin ratio, fiber property, matrix resin characteristics and fiber/resin ratio, but also on the reinforcing fiber alignment, processing method and fiber surface treatment. In the present study, random type, bi-directional type, and uni-directional type biocomposites with PBS and differently aligned silk fibroin fibers without and with electron beam irradiation at various doses are produced with different fiber loadings using extrusion/injection, compression, and extrusion/pultrusion processes, respectively. The effects of electron beam treatment on their mechanical and thermal properties are investigated in terms of tensile, flexural, impact, dynamic mechanical and thermal expansion properties, and fractured surfaces. Keywords: Biocomposites, Silk fibroin fiber, PBS, Processing, Electron beam, Properties