Aiming at some provisions in the code of design on building fire protection and prevention,analysed smoke preventing setting of smoke preventing staircase and antechamber,calculation of antechamber pressurizing air supply volume and design of smoke extraction,and gave the author′s personal opinions.

Analyses flow patterns of the pressurizing air simultaueous supply system insmoke preventing staircase and common antechamber, glves the detailed calculating formulasand it's apply example.

Discussing about the design of adding press and delivering wind in stair well underground guarding against smoke in the high-rise civil building;