This article examines the Augmented Reality (AR) development to become a new support for executing works in the construction worksite. In particular, the installing works of HVAC system after completion stage of masonry building (e.g. ventilator system, water and power supply, fire prevention system, et al) will be considered as the study subjects. In this work, the ventilator duct system will be operated in AR environment. The research proposes a new working manner by AR effects for technicians, and then establishes the AR system simultaneously. Actually, the proposed implementing process promises to be novelty and usability of research. Because the useful supports by AR technical can bridge the gap between desktop design documents and executing works in worksite that are enable to technicians (or workers) do their works in convenient environment. In implementing case, the technicians can check and do a comparison between the technical contents in design documents and virtual models of reality ventilator components in life position in worksite. In addition, they also can observe an AR animation guideline of assembling works in real-time. For technical issues, this work exploits an imagery marker-based AR tracking method in order to embed it into architecture works.