Big data is generated from sophisticated applications and is going to continue growing over the future years in a much diverse, larger and faster manner. Particularly, massive data with different formats sensed by various sensors, devices were from independent or connected components of Internet of Things (IoT) applications decide the diversity of applications and service type in IoT systems, which requires new technologies to manage big data with various format and to meet the requirements of various IoT applications. For such diverse business requirements, traditional systems are difficult to give a preferable solution due to their incapable system architectures. Consequently, to design new scalable system architectures is becoming a key research point for IoT big data management. This paper aims to provide a novel solution to manage big data of IoT systems, namely, the sea-cloud synergy model. Firstly, the designed architecture and the synergy mechanism of the model were discussed. Secondly, the design and implementation details of sea-side and cloudside of the sea-cloud synergy model were presented respectively. Finally, a demonstration system was built . Experimental experimental results verifies the preferable performance and feasibility of the designed sea-cloud synergy model.