The invention relates to a double-machine-head water chilling unit used for the rail transit industry. The double-machine-head water chilling unit comprises a compressor A, a compressor B, a condenser and an evaporator. The compressor A and the compressor B and different chambers in the condenser and the evaporator separately form two independent refrigerant circulation systems. A plurality of sets of heat exchange pipe bundles are separately arranged in all the chambers of the condenser and the evaporator, multi-process water side heat exchange can be achieved, the performance coefficient of the unit is greatly increased, and refrigeration requirements of rail transit operation stations are met.