The invention provides a construction method for a side slope. The construction method comprises the following steps that step 1, the side slope is constructed by fiber soil compacted at the outer side of a slope; step 2, a concrete side slope framework is formed at the outer side of the side slope; step 3, hexagonal bricks are constructed in the concrete side slope framework; and step 4, fiber soil is tamped and filled into the hexagonal bricks, wherein the fiber soil is made by mixing and stirring of pure soil, soil strengthening fiber and water, and stability of the side slope is improved by the fiber soil.