Abstract: Q960 high strength steel welded with self-developed flux cored wire. Weld metal with different Al element content were obtained by changing aluminium powder content in flux core composition. Tensile strength and toughness of weld metal were achieved by tensile and impact test at different test temperature. Combined with metallographic observation and scanning electron microscope observation,the influence mechanism of Al element on microstructure and properties of weld metal was analyzed. The results show that changing Al element content in weld metal has few effects on tensile strength and elongation,but has great effect on impact energy of weld metal. With Al element content being increased in weld metal,the impact energy increases firstly and then decreases. When Al content is low,Al₂O₃ oxides are easily formed in weld metal which is beneficial to nucleation and growth of acicular ferrite,which improve impact energy of weld metal. But when Al content is high,Al N nitride is easily formed,and δ-ferrite is formed,which results in the low impact energy of weld metal.