With proper erosion of sample surface and making a grid of crystal boundaries, the magnetic and crystalline microstructures of Sr-La-Co M-type ferrites of nominal composition of La0.2Sr08Fe11.8Co0.2 O19 (at.%) have been investigated by using magnetic force microscopy.By calculating average diameter and thickness, and average alignment degree of the grains of the ferrites, recognizing their domain pattes and calculating the proportion of grains with single domain or multi-domains, the Sr-La-Co M-type ferrites with high magnetic performance have been characterized at microcrystalline and micromagnetic level.In addition, we has interpreted why the grains always present plate-like domains.