A new environment-friendly wall material- the unfired brick is produced by using clay, carbide slag, fly ash and cement as the main raw materials，and certain amount of chemical excitator. The primary mixing ratio is designed on the basis of its mechanical properties and durability. When adopting water curing under normal temperature and atmosphere pressure，the compressive strength，flexural strength and frost resistance of the unfired brick are measured. The results reveal that the optimum mixing ratio for unfired brick is: Carbide slag 30%，fly ash 30%，cement 25% and clay 15%. For the unfired brick formed by vibration with the optimum mixing ratio，the min. compressive strength of each brick is more than 10 MPa, the overall properties meet the requirement as specified in standard JC 239—2001“Fly Ash Brick”.