The influence of Cr addition on the microstructure and stress corrosion cracking behavior of Al-6.5Zn-2Cu-1.5 Mg-0.05Ti alloy was investigated by microscopy characterization and slow strain rate tensile tests. In Cr-containing alloys, E (Al 18 Mg 3 Cr 2 ) phases precipitated from the matrix, which could serve as energetically preferred heterogeneous nucleation sites for η (Mg(Zn, Cu) 2 ) phases. Due to the decrease of η’ (MgZn 2 ) strengthening phases and the formation of η’ (MgZn 2 ) precipitate free zones, the strength of Cr-containing alloys was reduced to some extent. However, the crack propagation could be suppressed by the discrete distribution of grain boundary precipitates and the inhibition of recrystallization, leading to the increase of the elongation and the stress corrosion cracking resistance. With the addition of 0.15 wt% Cr, the comprehensive performance of Al-6.5Zn-2Cu-1.5 Mg-0.05Ti alloy was improved. Compared with the base alloy, the susceptibility index of stress corrosion cracking ( I SCC ) decreased by 82% and the elongation increased by 42% at the expense of partial strength (less than 5%). • With the addition of 0.15 wt% Cr, the comprehensive performance of Al-6.5Zn-2Cu-1.5 Mg-0.05Ti alloy was improved. • E (Al 18 Mg 3 Cr 2 ) phases could serve as energetically preferred heterogeneous nucleation sites for η (Mg(Zn, Cu) 2 ) phases. • Crack propagation of Cr-containing alloys was suppressed by the discrete distribution of GBPs and the inhibition of recrystallization.