Diploma thesis deals with the design of the condensing steam turbine with power output 23.63 MW at 5000 rpm and an efficiency of 84.17% after optimization. The turbine contains one controlled steam extraction and four bleeds. The steam mass flow required by controlled steam extraction is 0-75 t/h of a total mass flow to the turbine 105 t/h. Design of the steam turbine is preceded by calculation of heat balance of the cycle. Then the thermodynamic and strength calculation of regulation stage and reaction staging flow channel are made. Thermodynamic calculation of the flow channel consists of preliminary and detailed calculation. It is detailed calculation that leads to the turbine parameters optimization. The design also includes gland seali...