Through the characteristic analysis of the urban rail transit machine-electric equipment fault alarm, mining the type, frequency and multi-source heterogeneous characteristics of fault data, the paper forms the corresponding data system and knowledge discovery while it builds the mathematical modeling of machine electric equipment fault prediction based on grey theory, carries on the design and implementation of the corresponding system and algorithm. Besides, the paper does a city track traffic machine-electric equipment alarm data as a case which application results show that it can analyze the characteristic of machine-electric equipment fault data correctly and formats the early warning information auxiliary operation maintenance and overhaul.