In this paper, the grain growth, lattice strain, order behavior and electronic structure of FeSiAl powder were studied. Only the disorder bcc α-Fe peaks were exhibited after milling, and as the ball milling time increases, the internal strain rose and the grain size decreased. When the anneal temperature reached 773 K, we could see the obvious DO3 superlattice peak at (1 1 1), (2 0 0) and (3 1 1) plane. At the same time, the internal strain decreased and the grain size rose with the increment of annealing temperature. Annealing at temperatures above 773 K results in a long-range order (LRO) parameter about 0.67–0.76. This high LRO parameter further supports the observation of the formation of order DO3 structures. Furthermore, we found that the interaction between Fe and Si, Al atoms can decrease magnetic moment of the Fe atom. By the calculation of the empirical electron theory of solids and molecules, we confirmed that grinding process could change the electronic structure and the bond length difference ΔD of powder milled for 20 h had the smallest values.