The invention discloses a prefabricated concrete member steam curing production line and a steam curing method. The production line is composed of a steam heat source machine system, a steam transmission pipeline, a mold table and a steam curing shed, wherein water is converted into dry steam through the steam heat source machine, the dry steam is distributed to all pipelines through a steam distributing cylinder and finally enters the steam curing shed of a production line, valves on the steam transmission pipeline independently control mold table sets, temperature and humidity control is conducted through the steam curing shed and a temperature and humidity sensing probe, temperature control in a curing process is divided into temperature rise and then natural cooling, the heat preservation time of each stage is strictly controlled, and finally it is ensured that the strength of a component meets the specified requirement after the natural cooling. The prefabricated concrete member steam curing production line and the steam curing method are energy-saving, consumption-reducing, emission-reducing and efficiency-improving, the construction cost is low, the occupied area is small, the site utilization rate is high, the operation flexibility is high, the curing effect is good, the mold stripping time is shortened, the mold stripping strength is improved, the production efficiencyis improved, the component surface is crack-free, and the heat energy utilization rate is high.