The　solidification　behavior,　hot　cracking　and　microstructure　of　Al-7Zn-2.5Mg-Cu　alloy　were　investigated　with　hot　tear-linear　contraction　ZQS2000　twin　bar　tester　for　alloy,　OM　(optical　microscope),　SEM　(scanning　electron　microscope)　and　EDS　(energy　dispersive　spectrometer).　The　results　show　that　the　cooling　rate　and　linear　shrinkage　of　the　alloy　are　rapidly　increased　firstly　and　then　increased　slowly　during　the　solidification,　and　its　shrinkage　stress　is　generated　and　then　increased　dramatically　with　the　dendrites　formed　a　solid　skeleton.　The　formation　and　propagation　of　the　hot　crack　is　located　along　the　grain　boundary　of　the　α-Al　matrix　phase,　which　is　depended　on　the　rate　of　the　proeutectic　volumetric　shrinkage　and　the　ability　of　the　liquid　feeding　before　the　eutectic　reaction,　and　the　eutectic　shrinkage　in　the　eutectic　reaction　process.　The　hot　cracking　tendency　of　the　alloy　is　decreased　with　decrease　of　rate　of　the　proeutectic　volumetric　shrinkage,　the　stronger　ability　of　the　liquid　feeding　as　well　as　the　less　shrinkage　of　the　eutectic.