Different alloys with the minor Sc, Zr and Ti additions were prepared. Microstructures and mechanical properties of the alloys were studied. The results show that the Al-0.25%Sc-0.2%Zr alloy has smaller grain than that of the Al-0.25%Sc alloy, grains of which change from the columnar structure to the fine equiaxed structure because of 0.2%Zr addition. The as-cast Al-0.25%Sc-0.2%Zr-0.03%Ti alloy has the finest grain and the highest hardness of all the studied as-cast alloys. This behavior can be attributed to the fine Al3Sc, Al3(Sc,Zr) and Al3(Sc,Ti) particles, which not only act as the ideal nuclei for α(Al) but also produce grain-size strengthening and dispersion strengthening. The strength of the Al-0.25%Sc-0.2%Zr alloy is not higher than that of the Al-0.25%Sc alloy after hot extrusion because of the presence of Al3(Sc,Zr) particles with smaller misfit with Al than Al3Sc, which brings the transition of dislocation moving mechanism from Orowan bypassing to shearing of the particles.