In this work, the surface roughness of a porous ceramic composite material based on zirconium and magnesium oxides using the method of image analysis were studied. As the study materials ceramics of the ZrO2-MgO system in a wide range of component concentrations were selected. Ceramic samples had a developed, bimodal pore structure, formed due to the presence of voids between the ceramic powder particles and the introduction of pore-forming organic particles in the initial powder mixtures. Samples were sintered at different isothermal exposure time, from 10 to 600 min. The roughness was determined as the ratio of the surface section line length to the length of its projection on the images of fracture surface of ceramic samples obtained using a scanning electron microscope and a laser profilometer. The roughness value determined using a scanning electron microscope and using a laser profilometer was different, but their dependences on the sintering duration and composition were similar. It was found that dependence of the roughness on the composition and sintering duration, constructed in three-dimensional coordinates, makes it possible to distinguish the stages of solid-phase sintering of porous ceramics of the studied system. It was shown that roughness correlates with the average grain size and pores that change during isothermal exposure due to growth grains, volumetric shrinkage, leading to a decrease in the size of macropores, and an increase in micropores, due to their coalescence.