Abstract: The preparation of ecological hydraulic brick with steel slag as aggregate not only solves the pollution problem caused by the massive accumulation of steel slag but also reduces the excessive dependence on sand and gravel aggregate. In this paper, the ecological hydraulic brick was prepared by replacing sand aggregate with steel slag after heat sealing treatment. The effects of steel slag content, steel slag particle size and bone glue ratio on the water permeability, compressive strength and bending strength of ecological hydraulic brick were studied, and the relationship among the three parameters of ecological hydraulic brick was analyzed. The results showed that when the particle size of steel slag was 4 - 5.5 mm, its performance was better, and the water permeability, compressive strength and bending strength of the ecological hydraulic brick were 5.6 × 10^-2 cm/s, 45.45 MPa and 6.59 MPa, respectively. The apparent porosity directly affects the water permeability. A high apparent porosity contains more pores, which is more conducive to the passage of water, but it will lead to a decrease in the compressive and bending strengths. There is a negative linear correlation between water permeability and compressive strength but little correlation with bending strength. The relationship between permeability and compressive strength was explained, which would provide a new idea for preparing ecological hydraulic brick with both high permeability and high compressive strength.