A novel hierarchical MoS2@SnO2 hetero-nanoflower was successfully synthesized by a facile, two-step hydrothermal method without using any additives or surfactants. One possible growth mechanism of the hetero-nanostructure was presented in detail based on OH(-) ion-dependent experimental facts. Due to the formation of the p-n junctions and the increased specific surface area in the composites, an outstanding photocatalytic activity of the as-prepared sample was obtained by monitoring the photodegradation of methylene blue (MB). According to the data, after irradiation for 100 min, the remaining MB in solution is about 26% for MoS2 nanoflowers and 9.5% for MoS2@SnO2 hetero-nanoflowers. Moreover, an excellent field-emission performance was obtained from MoS2@SnO2 hetero-nanoflower relative to the pure MoS2 with the turn-on field decreasing from 4.2 V μm(-1) to 3.4 V μm(-1) and the threshold field decreasing from 6.2 V μm(-1) to 5.2 V μm(-1), which is mainly attributed to the increased field-emission points and MoS2-SnO2 heterojunction.