Abstract: A method and a system thereof for establishing a model for assessing construction site risk levels through deriving BIM-based hazard factors are proposed. The method includes step S110 of collecting similar study trends, step S120 of analyzing a CSI hazard factor profile database, step S130 of collecting construction company development cases and trends, step S200 of establishing a classification system of a risk assessment DB (110) and including step S210 of systematizing a construction site category, step S220 of deriving a quantitative risk level calculation method, and step S230 of analyzing current risk assessment, step S300 of developing a framework and including step S310 of deriving a construction site hazard factor visualization method and step S320 of developing a risk assessment model framework, step S500 of transmitting BIM-based risk assessment model data, and receiving feedback including supplemented data, and step S600 of establishing the BIM-based risk assessment model.