1. A context inference system, comprising: a mobile device, comprising: a information receiving unit, receiving at least one context information; and a context operation platform, coupled to the information receiving unit and performing a context inference process, the context operation platform comprising: an information collection module, collecting information used for inferring a context; a data classification and storage module, storing and classifying a user preference information of a user; and a inference module, inferring the context; and at least one information sending unit, transmitting the at least one context information to the mobile device, wherein the at least one information sending unit is mounted on at least one object, and the at least one context information is a related information of the at least one object; wherein the context operation platform performs the context inference process based on the received context information and the user preference information in order to forecast a need of the user and provide a recommendation information to the user.