Abstract: To essentially investigate the effect-mechanism of water contents (w), curing agent dosages (W_g) and ages (T) on the mechanical behavior of stabilized waste sludge, a series of Scanning Electron Microscope (SEM) tests under different w, W_g and T are conducted by taking the waste sludge solidified by magnesium oxysulfate cement as the research object. The effects of w, W_g and T on the micro-parameters of the stabilized sludge such as contact area ratio (R_CA), average abundance (C_m) and fractal dimension (D) are addressed by using the Image Pro Plus. The results show that the increase in w will prevent the hydration of magnesium oxysulfate cement and enhance the dispersibility of the microstructure of the stabilized sludge, further decrease the values of R_CA and C_m and improve the value of D. Among the aforementioned three factors, T has a significant influence on the development of R_CA and D, and W_g plays an important role in the evolution of C_m.