The invention relates to a water spray system with a screw-type water vapor compressor unit. The water spray system comprises a soft water tank, a filter, an in-front-of-pump cutoff valve, a water spray pump, a behind-pump non-return-type straight-through cutoff valve, a spray nozzle and a water vapor compressor, wherein the interior of the soft water tank is provided with an empty cavity; the upper end of the soft water tank is provided with a water inlet communicated with the empty cavity; the lower end of the soft water tank is provided with a first water outlet; the first water outlet is connected with an inlet of the filter through a water pipe; an outlet of the filter is connected with an inlet of a water spray pump through a water pipe; an outlet of the water spray pump is connectedwith the spray nozzle; a water pipe between the water spray pump and the spray nozzle is provided with the behind-pump non-return-type straight-through cutoff valve; the spray nozzle faces an air inlet of the water vapor compressor. Soft water of the water spray system enters the empty cavity of the soft water tank through a water inlet pipe, is filtered through the filter, then enters the waterspray pump to be pressurized, finally, is sprayed into the air inlet of the water vapor compressor through the spray nozzle, is uniformly mixed with low-pressure vapor at the air inlet of the water vapor compressor, enters a cavity body of the water vapor compressor, and is compressed into required high-pressure vapor.