Introduction  In order to analyze the impact of the single rack-joint side bunker scheme on the capacity， investment and maintenance of the main building of 350 MW thermoelectric unit.

  Method  Through the introduction of the optimization process of the layout pattern and structure size of the front coal bunker， side coal bunker， single row rack and single frame of the 2x350 MW off-site expansion of the supercritical unit project of Guodian Lanzhou thermal power Co.， Ltd.， the impact of different layout plans of the project on the investment in the early stage and the operation and maintenance in the later stage was compared.

  Result  On the premise of facilitating safe and normal operation and maintenance of the unit， the project adopts this scheme to achieve a good level of 0.287 m³ /kW.

  Conclusion  Through analysis， the main building arrangement design scheme has a good practical value， which can be used as a reference for similar urban cogeneration projects.