To study the energy output law of the suspended AlH₃ dust in explosion and release process， a modified 20 L ball explosion test system was used to study the explosion pressure and flame propagation law in closed and venting conditions alternately. The results showed that the lower explosion limit concentration of suspended AlH₃ in a closed system decreased from 40 g·m^-3 to 30 g·m^-3 comparing with aluminum powder， indicating that the hydrogen released by the burning AlH₃ accelerated the entire chemical reaction process. In addition， both the maximum explosion pressure and explosion pressure rise rate of AlH₃ dust explosion in a closed system were higher than that of the aluminum powder. The maximum explosion pressure rose from 1.02 MPa to 1.15 MPa， indicating that a combustible gas-dust composite system was formed due to the release of hydrogen to exacerbate the violence of the explosion energy release process. Under venting conditions， when the concentration of AlH₃ dust was 500 g·m^-3， the explosion pressure （p） and pressure rise rate （dp/dt） decreased the most， reaching 43% and 30% respectively， indicating explosion venting can effectively reduce explosion damage. Moreover， it was concluded that the length and speed of the explosion vent flame reached the peak values when the concentration of AlH₃ was 750 g·m^-3， meanwhile the probability and frequency of multiple flames presented a positive correlation with the concentration.