Sulpho-aluminate expansive cementitious composite is proved to be one of the most effective ways to prevent concrete cracking too soon． Mix design of sulpho-aluminate expansive cementitious composite complete- ly depends on experience and experiments at present． This method ignores the influence of expansion behavior which hinders the application of sulpho-aluminate expansive cementitious composite． The workability，free ex- pansion property，flexural strength and compressive strength of sulpho-aluminate expansive cementitious com- posite have been investigated by tests． The relationship between expansion ratio and mix design parameters such as curing age，water-cement ratio and cement abundance coefficient is deduced according to the experimental statistics． A new simplified approach to mix design of sulpho-aluminate expansive cementitious composite is pro- posed as a reference for construction application，which avoids experiments and experience．