Abstract: Methods, devices, and systems for building system maintenance using mixed reality are described herein. One mixed reality computing device for building system maintenance can include a mixed reality display, a memory, and a processor to execute executable instructions stored in the memory to receive a work order for a device in a building, determine a location of the mixed reality computing device in the building, and display virtual information about the device on the mixed reality display based on the location of the mixed reality computing device in the building, where the displayed virtual information includes information about fixing a fault of the device, and where the virtual information displayed on the mixed reality display is overlaid over an area of the mixed reality display based on a field of view of the mixed reality computing device.