Al-Ti-B-Sr-RE master alloys were prepared firstly by the reaction of complex halide salts with molten aluminum at 800°C, and then the addition of Al-RE and Al-Sr master alloys into the melt. The constituent phase and microstructure were characterized by XRD, optical microscope (OM) and scanning electron microscope (SEM). The element content was analyzed by spectrometer, X-ray fluorescence spectrometry and electron probe microscope. Ti2Al20RE, SrB6, LaB6, Al4Sr and Al11La3 are the constituent phases in these master alloys. The constituent phases containing Sr and RE in the Al-Ti-B master alloy depend on the ratio of Ti and B. The critical ratio of Ti and B is 2.2:1. Obviously, SrB6 and LaB6 phases are the reaction products of AlB2 with Sr or La during master alloy fabrication. The two layer lump-like Ti-Al-RE particles formation mechanism is proposed.