In the alloy with solute content higher than the limiting solubility, the solute atoms failing to dissolve will precipitate from the solid solution and form precipitations. In this study, the Portevin-Le Chatelier (P-LC) effects in annealed 5456 and 5052 aluminum alloys with different precipitation content are investigated under different applied strain rates respectively. The findings suggest that precipitations have a significant effect on the P-LC effect and different precipitation content has different effects. Furthermore, the solute diffusion is pipe diffusion in 5052 alloy with lower precipitation content. However, for 5456 alloy with higher precipitation content, the diffusion is no longer the case but more complex.