The trapezoidal continuous casting billet Al-5Ti-1B-0.2Cu intermediate alloy was investigated by solid solution treatment at different solid solution temperatures, followed by transverse and longitudinal hot compression deformation at different deformation temperatures, different deformation rates and different deformation directions. To study the effects of Cu element addition, solid solution treatment and hot compression on the microstructure and dimensional inhomogeneous deformation of second phase particles. The results show that there are four types of second phase particles (Ti_1-X,Al_X)B₂, Al₇Cu₂Fe, TiB₂ and TiAl₃ after solid solution treatment at 600 ℃/4h. When Cu is present, the Al-Cu-Fe phase is generated to increase the number of particles in the second phase. At the same deformation degree and deformation temperature, the average size of TiAl₃ particles decreases with increasing deformation rate (0.01, 0.1, 1s_-1^{), while TiB}₂ particles tend to be more diffusely distributed. The second phase particles TiAl₃ are more uniform after transverse compression deformation, but the TiAl₃ particles are finer after longitudinal compression deformation, while the size and distribution of TiB₂ particles in transverse compression and longitudinal compression are basically the same. The dimensional inhomogeneous plastic deformation of the trapezoidal continuous casting billet is more favorable to the size and distribution of the second phase particles TiAl₃ and TiB₂.