Complex information systems are characterized by high difficulty in performing tasks, changeable situation environments, and complex information structures. From a design perspective, enabling users to have continuous and efficient situational awareness is one of the key goals of human-computer interaction design. The construction method of user mental model based on situational awareness elements is explored for complex information interface to guide the design of human-computer interaction. Based on the mental model theory, the situation awareness theory is introduced. Taking the remote control of unmanned vehicle path planning tasks as an example, the situation awareness elements required to complete the task are extracted. On basis of this, the construction method of the user mental model is discussed. The construction method of user mental model based on situation awareness elements can improve the matching degree of interface information presentation, interaction mode and user mental model, thereby improving the user’s continuous situation awareness ability, and providing new ideas and theories for the interface design of complex information systems.