In order to reduce construction costs and achieve digitalization of construction cost control, this paper studies the digitalization model of construction costs based on an improved ABC algorithm, aiming to better adapt to the special needs and complexity of the construction industry. The ABC (Artificial Bee Colony) algorithm, as an optimization algorithm, has been widely applied in many fields, such as intelligent search, engineering optimization, financial markets, and so on. The construction cost control system based on the ABC algorithm can classify and store data information, thereby achieving the goal of information sharing and collaborative work. This article establishes a cost benefit chain estimation model for green building construction using cost constraint indicators such as construction technology, materials, labor, and technology as explanatory variables. By evaluating the equivalent value of fixed cost constraints, dynamic and adaptive predictions of building costs are made. The experimental results show that the use of an improved ABC algorithm based digital model for building cost control can significantly reduce building cost expenses. On the basis of ensuring quality and efficiency, a construction cost of 188,000 yuan was saved in the experiment, confirming that the model can effectively control construction costs.