Crack occurrence is a visual representation for brick masonry damage. In this paper, crack evolvement law of ancient brick masonry under uniaxial compressive loading after freeze-thaw cycles was investigated. The loading-deformation curve and crack data of ancient brick masonry were recorded. For each masonry sample, its initial cracking load was determined synthetically by three reference values based on loading-deformation curve, length of single crack, and crack development. After the crack length at every loading level was obtained, the normalization processing was performed. The trilinear model was used to simulate the relationship between the crack length and loading level. Crack of the ancient brick masonry occurred earlier and faster than that of modern brick masonry: the value range of initial cracking load was from 0.4 fm（compressive strength） to 0.6 fm，which averaged about 0.52 fm； when the stress reached 0.7 fm，critical crack was initiated; when the stress reached 0.93 fm，masonry entered into the ultimate state. The masonry damage was described by crack density, which was defined as the crack length per unit area. The development rule of crack density was proposed with a final value of 8.7 m/m2. Compared with the results of similar tests in references, it was found that crack density was a relatively stable indicator, which has good potential for further study and application.