Mechanical milled SUS316L stainless steel powder is applied to hot roll sintering (HRS) process. Microstructure and mechanical properties of the HRS material is investigated. Microstructure of material produced by HRS process consists of the shell and core hybrid microstructure, that is, a shell structure with nano grains and a core structure with work-hardened coarse grains. The fine grain structure corresponding to the shell area has (austenite + sigma) nano duplex structure. Work-hardened structure in the core area composes of an austenite phase. The HRS material demonstrates not only superior strength but also enough elongation. Mechanical properties are strongly influenced by the shell/core structure, such as grain size, shell/core size and/or the volume fraction. The shell and core nano-duplex hybrid microstructure by the HRS process has been proved to be very effective to improve mechanical properties.