The microstructure and mechanical properties of Nb micro alloyed low carbon steel strip are studied. The grain orientation and boundary characteristic of bainitic ferrite are investigated by using the EBSD technique. The as-cast strip and hot rolled strip are observed by the TEM. Results show that the solidification structure of the Nb micro alloyed low carbon steel is composed of two columnar zones and an equiaxed zone located in the middle of the strip. The microstructure of strip is predominantly bainite and a few polygon ferrite. The EBSD results indicate that there are large of 0°~15 low-angle grain boundaries. TEM examination has not revealed any Nb precipitation in as-cast strip, but there are globular Nb(C,N) precipitation with the size ranging from 5 to 20nm after being hot rolled. The microstructure of the hot rolled strip is consisted of fine ferrite and a few pearlite. The hot rolled strip has attractive mechanical properties. Its elongation reached more than 23%, which is much better than the as-cast strip.