It is well accepted that the interaction between solute atom and precipitated phase leads to dynamic strain aging (DSA). In this research solution treatments at different temperatures are adopted to control the solute concentration in solid solution and precipitated phase content in the Al-4.5wt%Cu alloy material, and their influences on dislocation movement are analyzed by subsequent tensile experiments on these treated material specimens, and the corresponding micro-mechanism of DSA is discussed. It is found that, when the solution treatment temperature is reduced stepwise from 500℃, the amplitude of the serrated yielding decreases until it reaches a minimum at 300℃, whereas the amplitude begins to increase as the solution treatment temperature is reduced continually to 100℃. Meanwhile, the heat-treatment also affects the propagation characteristics of shear bands. The experimental results also show that, when the solution treatment temperature is higher than 300℃, the solute concentration is the key factor influencing DSA. However, when the solution treatment temperature is lower than 300℃, the intensity of DSA is determined by precipitated phase density. In the case of room temperature, the micro-mechanism of DSA is found to be primarily governed by precipitated phases.