The work presented in this paper focuses on the molding technical and mechanical properties of cotton stalk block. Cotton stalk block is a new type of ecological filling materials. The previous test data and practical experience show that the major three factors affecting the compressive strength of the block are the glue consumption, the density of block and the sand content of block. In this paper, the method of orthogonal experiment is used to analyze the molding technology of cotton stalk blocks and the above three factors (glue consumption, density and sand content of block). The research results show that, the glue consumption and the density have significant effect on the compressive strength of the block, but the effect of sand content of block is less. In additional, an optimal combination of the three factors is obtained. Based on this combination, the compressive strength of the block can reach to1.55 MPa, which can meet the strength requirement of the filling materials.