The invention discloses a coal and gas outburst predicting method, device and system. The method includes the steps that at least one basic parameter of shaped coal and a data value corresponding to the basic parameter are acquired; the data value corresponding to the basic parameter is input into a predicted outburst model, and a plurality of predictive parameters and outburst results corresponding to the predicative parameters are determined; according to grey relational analysis, outburst pre-warning indexes are obtained according to the predictive parameters and the outburst results; and according to the outburst pre-warning indexes and pre-warning levels corresponding to the outburst pre-warning indexes, outburst pre-warning levels are obtained, so that the coal and gas outburst predicting reasonability, accuracy and reliability is improved, the occurrence rate of casualty accidents is lowered, and the safety of underground life and property is greatly guaranteed.