To evaluate the effect of split structure in the burner exit on NOx emission and flame stability, an experimental study was carried out in confined commercial LPG/air flames. Four burner geometries, such as a conventional circular burner and three burners with split structure, were selected. The burners with split structure have a narrower flame stability regime than a conventional circular one, because of the non-uniform burner rim. The results show that a variable related to the geometry at the burner exit should be included in the correlation on fuel discharge velocity for flame blowout. The burner with a split structure on the fuel discharge side reduces NOx emission by about 5% compared with a circular burner. This is because flame temperature drops owing to flame elongation and the increase of radiative heat losses, caused by partially luminous flames in the flame front, Meanwhile, at the burners with split structure on the air discharge side and both fuel and air discharge sides, NOx emission is increased probably due to the elongation of the blue flame in the flame front. It is considered that split structure in the burner exit does not always aid NOx reduction and the burner with split structure on the fuel discharge side is effective to abate the NOx emission.