Software Defined Satellite Net-works (SDSN) are proposed to solve the prob-lems in traditional satellite networks, such as time-consuming configuration and inflexible traffic scheduling. The emerging application of small satellite and research of SDSN make it possible for satellite networks to provide flexible network services. Service Function Chain (SFC) can satisfy this need. In this pa-per, we are motivated to investigate applying SFC in the small satellite-based SDSN for ser-vice delivery. We introduce the structure of the multi-layer constellation-based SDSN. Then, we describe two deployment patts of SFC in SDSN, the Multi-Domain (MD) patt and the Satellite Formation (SF) patt. We pro-pose two algorithms, SFP-MD, and SFP-SF, to calculate the Service Function Path (SFP). We implement the algorithms and conduct contrast experiments in our prototype. Finally, we summarize the applicable conditions of two deployment patts according to the ex-perimental results in terms of hops, delay, and packet loss rate.