X-ray diffraction line profile analysis technique was employed to investigate the dislocation density evolution during high temperature creep of Mg-3Al-1Zn alloy. The microstrains within the domain and dislocation density were calculated by the simplified Williamson-Hall and Williamson-Smallman methods. Further analysis on the possible dynamic recrystallization (DRX) and dynamic recovery (DRV) shows a relation between the number of dynamically recrystallized grains and the dislocation density. At constant temperature, higher stresses lead to more DRX and an enhancement on the dislocation density; whereas, at lower stresses the DRV is dominant leading to decrease in the dislocation density.