We synthesize MAl12O19 (M = Ca, Sr, Ba) singly doped with Eu2+ or Cr3+ and co-doped with Eu2+ and Cr3+ by high-temperature solid-state reaction under reducing atmosphere. It is observed that there exit energy transfers from Eu2+ to Cr3+ in MAl12O19 (M = Ca, Sr, Ba) hosts. Although the MAl12O19 (M= Ca, Sr, Ba) hosts have similar crystal structures, the energy transfer efficienies and the conversion rates of the blue light to the red light are different. Both experiment and calculation show that the energy transfer from Eu to Cr in CaAl12O19 host is most efficient, and the ratio of the red emission to the blue emission in CaAl12O19 host is the highest among the three different hosts.