4350 m3 blast furnace of TISCO blowed down for 18 h and 50 min without plan on Feb.28, 2010, because the expansion joint in roof center pipe run gas. With a view to metal temperature，low burden load，s point of blast furnace and conditions of blast furnace， the blast rate and oxygen enrichment value were restored through 3 steps. The furnace conditions recovered successfully with more coal, enough blast temperature and reasonable operation of cast house, etc.