The invention discloses an online three-dimensional visualization method for a construction project model, and belongs to the field of construction projects. The online three-dimensional visualization method for the construction project model comprises the following steps: firstly, carrying out three-dimensional simulation based on a high-precision terrain by using a design achievement of a construction project; secondly, converting space data of a three-dimensional model of the construction project into a high-precision digital elevation model, and fusing the high-precision digital elevation model with low-precision digital elevation model data; thirdly, inlaying dependent textures of the three-dimensional model of the construction project and publicly accessible large-range image data; and finally, carrying out additive fusion on the basis of the fused digital elevation model and the inlaid images to obtain a visualized construction project model. The three-dimensional model of the construction project is established by the high-precision data resources; geographic information which can be acquired from the internet is used as the background, and is fused with the three-dimensional model of the construction project, the fused data resources are shown to the public, therefore, the contradiction between resource utilization and a privacy policy is solved effectively, and the service ability of the geographic information resources is improved greatly.