This paper presents a pneumatic energy absorption system which can extend the energy-absorption beam automatically just before crash. The system consists of thin-shell energy absorption structure, pneumatic equipment and control system. When the control system detectives a crash accident is unavoidable, the pneumatic equipment will extend the energy absorption beam which is fixed in thin-shell energy absorption structure immediately to increase energy absorption space. This system has been equipped on a mass produced bus, and it indicates that the length of energy absorption space can be increased more than 230 mm instantaneously before a crash accident occurs. The time used to extend the energy absorption beam is less than 100ms.