The invention discloses an ecological remediation-type precast concrete plank and a method for reconstructing a river hard protection bank as well as restoring riverbed, wherein the precast concrete plank employs concrete to precast, the concrete comprises the following components: 400-700kg/m<3> of porous aggregate; 200-250kg/m<3> of low alkalescence cementing material, 40-60kg/m<3> of granular repairing agent, 3-7kg/m<3> of high efficiency additive and 50-90kg/m<3>. The ecological reconstruction method that the ecological remediation-type precast concrete plank is employed at bottom of original hard protection bank and riverbed has the advantages of saved resource, less investment, short construction period and fast effectiveness, and overcomes the difficulty of underwater construction of the concrete. Through the reconstruction method, a water and land ecological system chain is improved, pollutants such as an organic matter, nitrogen and phosphorus and heavy metals in water can be simultaneously absorbed, then pollutants can be removed through combined action of animals and plants as well as microbes, in-situ regeneration of an adsorbent is realized, adsorption capacity enables in-situ recovery, and long-term continuous ecological water purification effect can be reached.