The relative intensities, $\gamma = I(K_{\alpha}L^1)/I(K_{\alpha_{1,2}})$, $\eta = I(K_{\alpha}L^2)/I(K_{\alpha}L^1)$ and $\chi = I(K_{\alpha}L^3)/I(K_{\alpha}L^1)$, of x-ray emission $K_{\alpha_{1,2}}$, $K_{\alpha}L^1$, $K_{\alpha}L^2$, and $K_{\alpha}L^3$ lines’ groups of aluminium are experimentally studied under the excitation by electron impact in the range of accelerating voltages $U =$ 4.5–100 kV. The model of $K_{\alpha}$ x-ray emission has been proposed and takes into account the main channels of multiply ionized $KL^n_{2,3}$ states’ decay. As found, the probabilities of creation of $KL_{2,3}$ configuration ($P_1$), $KL^2_{2,3}$ configuration ($P_2$) and $KL^3_{2,3}$ configuration ($P_3$) monotonically decrease when bombarding-electron energy $E$ > 20 keV. The observed decrease of the $P_1$, $P_2$ and $P_3$ values can be explained by decreasing of the average energy transferred to the atom in electron–atom collision. The $P_2$ and $P_3$ probabilities significantly exceed (by 1.6 to 2.5 times) their values predicted within the shake-off approximation of simultaneous independent ejecting of two and three $2p$ electrons that indicates a significant role of the $2p–2p$ electron correlations in $KL^n_{2,3}$ ionization processes. As shown, the $P_{21} = P_{2}/P_{1}$ and $P_{31} = P_{3}/P_{1}$ ratios are practically constant in the whole range of accelerating voltages and are the parameters characterizing the values of $2p–2p$ electron correlations.