A rapidly solidified Al-5Ti-1B master alloy prepared by the in-rotating-liquid spinning process has been investigated. It has been found that the in-rotating-liquid spinning process is a potential rapid solidification method to realize the continuous production of the master alloy wire on a large scale. The microstructure of the Al-5Ti-1B was evidently improved after being rapidly solidified. The agglomeration of the TiB2 particle was significantly decreased. Consequently, the grain size of the purity aluminium refined by the rapidly solidified Al-5Ti-1B was reduced by 15% compared with that refined by the master alloy prepared under normal conditions.