The invention discloses a railway engineering mechanical power system which comprises an internal combustion engine generator set, a converter as well as a magnesium excitation control module and a CAN (Controller Area Network) network control module and an MVB (Multifunction Vehicle Bus)/CAN module, wherein electric energy output from the internal combustion engine generator set is converted by the converter to supply power to a traction motor; the internal combustion engine generator set comprises an internal combustion engine and a power generator which is connected with the internal combustion engine; the magnesium excitation control module is connected with the power generator; the power generator is driven by the internal combustion engine to output electric energy to the converter; and the power generator is subjected to magnesium excitation control of the magnesium excitation control module. By adopting the power system, the technical problems that a conventional railway engineering internal combustion hydraulic power mode is complex to maintain, hydraulic oil can be leaked off and the environment can be seriously polluted are solved.