Temporal networks are such networks where nodes and interactions may appear and disappear at various time scales, which are ubiquitous in our economy, nature and society. Inspired by the description of a static network as a linear time-invariant (LTI) system in Lin and Liu's work, in this paper we consider a temporal network associated with a linear time-variant (LTV) system, and focus on structural controllability of temporal networks through a graphic tool with the time-ordered graph model. Both graphic interpretation and illustrative examples are given to understand structural controllability of temporal networks.