In the teaching of construction technology of urban underground engineering, image spatial representation and teaching demonstration tools are needed when it involves unusual architectural space and the construction process which is difficult to express. BIM can provide excellent information communication and expression ability and can be applied to the teaching practice of construction technology of urban underground engineering. Urban underground engineering components are classified and viewed effectively by embedding Unity3D engine to Winform; urban underground space roaming program has been developed by Navisworks API, which realizes virtual space roaming under the gravity. And a demo player for construction process is developed. The conclusion has certain significance on the teaching of construction technology of urban underground engineering.

Mixed reality can combine virtual world and real world, which provides designers a whole new way of demonstration once applied to construction engineering. Starting from demand, this paper discusses how mixed reality can be applied to field of building engineering; Through massive testing, key technologies of mixed reality in large space of construction engineering are studied. This research provides demand and technical solutions for the practical application of mixed reality technology in construction engineering.

Compared with the virtual reality (VR) technology and augmented reality (AR) technology, the mixed reality (MR) technology owns the advantages of flexibility, interactivity and real-time performance. Therefore, the MR technology has gradually become an important way to realize intelligence and informationization in different industries. The application of building information model (BIM) technology has promoted the informatization of the construction industry, while the combination of MR + BIM becomes a new research direction in our construction industry. Through using the Hololens developed by Microsoft, this paper explores the application of BIM technology in construction, which is able to enhance the visualization, real-time and high-efficiency construction industry, which provide new ideas and new methods for building engineering intelligent and informatization.

Engineering construction needs visual progress management tools to integrate BIM and VR to develop a visualized and multi-terminal construction progress demonstration system with rich information. Building the standard construction model with Revit, this article modifies the texture of materials using 3DMAX and then imports the model to Unity3D SO as to develop a cross-platform construction progress system. Model information in Revit is transmitted to Unity3D in IFC format, which can be easily released to the PC. Web and mobile terminal and provide better service for construction management.