In order to reduce fluorine pollution, partial fluoride could be replaced by Li2O in mould flux. The effects of Li2O on properties of low fluoride content mould flux for high speed continuous casting were studied. The properties included melting temperature, viscosity, fluidity, surface tension and Al2O3 inclusion adsorption. The results showed that with the increase of Li2O content, melting temperature and viscosity of mould flux decreased obviously, fluidity increased, surface tension changed little, and Al2O3 inclusion adsorption of mould flux increased. In order to play an effective role, the appropriate Li2O content should be less than 4 per cent. The crystallization state of mould flux changed after slag adsorbed Al2O3. There were some small cuspidine and wollastonite crystals in the sample.