The invention belongs to the information technology field and discloses an information system risk early warning model construction method based on big data. An information system risk early warning model is established, wherein the information system risk model comprises three sub-models which are an information system basic infrastructure evaluation mathematic model, an information system real-time reliable evaluation mathematic model and an information system historic operation evaluation mathematic model. On the basis of the three sub-models, the invention realizes a risk pre-alarming on the information system, realizes information system risk alarming before the fault, greatly improves the information system maintenance efficiency, promotes the information to develop toward the more delicate, more coordinated, and more efficient direction.