The collapse of TV iron tower of the teaching TV station at Bozhou,Anhui province on 30 August 1999 is caused by a squall.The iron tower endured much great wind beyond the limit criterion in GBJ9 87.Additional,the iron tower locates on one high building near to another high building,these two high buildings form a ′hom′ that makes the wind speed swifter than otherwhere,the high speed wind collapses the TV iron towere.This conclusion is beneficial to the study of high building and iron towere building criterion.