To study the effect of magnesium hydride (MgH₂) on the ignition performance of Al and B mixed system, a new high energy hydrogen-containing ternary metal fuel was prepared by mechanical mixing method using aluminum powder as matrix, boron powder as high energy metal additive, and magnesium hydride (MgH₂) as active metal additive The minimum ignition energy (MIE) of Al, B and MgH₂ was determined by a 1.2 L Hartmann tube apparatus and the MIE of binary metal mixtures (Al-MgH₂, B-MgH₂) under the conditions of different MgH₂ contents and ternary metal mixture Al-B-MgH₂ under the conditions of different boron and MgH₂ contents was compared and studied. Results show that the MIE of Al and MgH₂ is lower, their values of MIE are 80-100 mJ, 5-10 mJ, respectively, the MIE of B is higher, whose MIE is more than 1000 mJ. With the increase of MgH₂ content in the mixture from 10% to 30%, the MIE of Al-MgH₂ and B-MgH₂ reduces from 50-70 mJ and more than 1000 mJ to 10-20 mJ and 480-500 mJ, respectively. With decreasing the boron content in the ternary mixture Al-B-MgH₂ from 25% to 10%, whose MIE also reduces from 700-800 mJ to 20-30 mJ and when the boron content is certain value, the increase of MgH₂ content can significantly decrease the MIE of Al-B-MgH₂ metal mixture. When the content of boron powder is reduced to 10%, the MIE of Al-B-MgH₂ metal mixture powder can be maintained in the range of 20-40 mJ.