2219， 2A14 and 2195 alloys were three kinds of structural materials for aerospace application. Particularly， 2195 alloy was more and more widely used in aerospace industry because of its low density， high specific strength and rigidity and etc. By using the in-situ observation system of high temperature metallography， the microstructure evolution and phase transformation of three kinds of aluminum alloys in strengthened condition from room temperature （about 25 ℃） to zero strength temperature （about 600~660 ℃） at a heating rate of 50K/min was investigated. The results show that three kinds of aluminum alloys melt at a temperature higher than the solidus curve， the first melting position lies around the spherical phase （containing Al， Cu）， and that the massive phases （containing Al， Cu， Fe， etc） melt at last. After the cycled-water solidification process， the micro-hardness of the re-solidified materials decreases by about 50%， indicating that the strengthening phase in the matrix decreases. The Cu content of primary α phase decreases， and most of the Cu element remains at the grain boundaries， forming net-like Cu-rich phase whose composition is close to eutectic composition， and a few massive phases that do not dissolve completely are forced to the grain boundaries. As a result of the comparison of three alloys， the conclusion is drawn that 2195 alloy， which has the smallest solid-liquid temperature interval， is susceptible to thermal cracks since the Cu-rich liquid films are easily torn apart by thermal stress.