Rebar engineering is a construction method for building structures that is critical to the earthquake resistance of the entire building. The construction process and quality of rebar have always been valued by the construction industry, and it is imperative to improve the quality of reinforcement construction to reduce injuries. In recent years, Building Information Modeling (BIM) technology has been widely applied in the stages of design, operation and maintenance, but less in the construction phase. For rebar works in the construction phase, a BIM model of rebar can facilitate the development of a solution because 3D visualization of the model makes it easier to understand the problem. However, to apply the rebar BIM model to practice, it is necessary to build a model with the rebar takeoff to meet the actual construction status. Thus, how to optimize the takeoff of rebar from the completed 3D model has practical research value. This study takes the on-site construction of rebar as an example. For the main component, a BIM model is built with Tekla software to produce practical rebar takeoff plans with an A-star algorithm based on legal norms and construction feasibility that can reduce the amount of excess rebar material. It also chooses the best rebar takeoff plan to build the rebar BIM model. As a result, the relevant personnel who use the rebar BIM model can correctly solve the actual problems with the BIM model.