The 2024 aluminium alloy tubes were prepared by squeeze casting. The dissolution of the intermetallic phases was studied, and the effect of solution on strengthening in 2024 casting alloys during heat treatment was analyzed. The results showed that the U phase(Al2Cu) and S phase (Al2CuMg) dissolved gradually in the initial stage of solution，but Cu element still existed around grain boundary. With the time of solution treatment prolonging，the amounts of Cu and Mg in matrix increased. However, the function of solution strengthening mainly originates from Cu and Mg dissolve． The alloys underwent solution treated at 495 ℃ and they were aged for 12 h hours at 190 ℃ afterwards, the tensile strength of the alloy reaches to 435 MPa and the specific elongation of the alloy is up to 6.9%.