The utility model relates to a gas and steam combined cycle system field to a turbine unit and a gas and steam combined cycle system for being used for the gas and steam combined cycle system is disclosed, turbine unit includes exhaust -heat boiler (1), steam turbine (2), generator (3), condenser (4) and condensate water main pump (5), the rotor of generator with the spindle drive of steam turbine connects, be provided with between the intermediate pressure cylinder of steam turbine and the low pressure jar clutch (6), the steam extraction of steam turbine passes through the condensing pipeline in proper order via setting up in this condensing pipeline the condenser with the condensate water main pump return to exhaust -heat boiler, turbine unit still includes condensate water booster pump (7), and this condensate water booster pump sets up the condenser with between the condensate water main pump in the condensing pipeline, the condensate water booster pump is variable frequency pump. The utility model discloses a turbine unit has the equal lower advantage of energy consumption under different work condition.