Recycling clay brick becomes extremely urgent with the demolishment of residential buildings, and the most common processing option of clay brick waste is buried in landfills which lead to serious environmental pollution. Meanwhile, the process of recycling clay brick is immature and there is limited knowledge and standards of recycling clay brick waste. This thesis reports an experiment to test physical and mechanical prosperities of clay brick aggregate (CBA). Mortar specimens were conducted by using different prewetting times, replacement rates and water/cement ratios. Absorption and water-releasing abilities were discussed; compressive strength and flexural strength were conducted for strength test. Flowability and internal humidity tests were also presented. The results demonstrated that mortar specimens with 30% of replacement rate of CBA, and 0.28 of water/cement ratio of mixes present the optimal workability. By comparing with recycled concrete aggregate (RCA), CBA also showed satisfactory performance in the mortar specimens.