Plastic concrete was prepared by low liquid limit red clay, sand and gravel to discuss the effect of low liquid limit red clay on concrete workability and mechanical properties. The effect of low liquid limit red clay content and water cement ratio on plastic concrete workability, compressive strength, splitting strength, modulus of elasticity was discussed in the paper. The results showed that: low liquid limit red clay can improve liquidity, adhesiveness and water retention of the concrete, after 1 hour slump remained above 173 mm, and red clay can significantly delay initial setting and final setting time of concrete and significantly reduce apparent density of concrete. Compressive strength, splitting strength of concrete increases with logarithmic relationship with extension of curing age when clay replaces cement. Relatively speaking, the effect of clay content on concrete compressive strength was higher than water cement ratio. The larger the clay content is, the smaller the elastic modulus of the concrete are, which can be predicted by the linear relationship between compressive strength and elastic modulus of concrete.