The invention discloses a construction technique for an environment-friendly cast-in-situ bored pile provided with a wall protecting tube. The construction technique is characterized by comprising the following steps that (1) the wall protecting tube is arranged and piled underground of a construction site by means of external force, wherein the inner diameter of the wall protecting tube is larger than the drilling diameter of the cast-in-situ bored pile; the piled depth (h1) of the wall protecting tube is determined according to the following conditions that if the designed depth (h2) of the cast-in-situ bored pile is equal to or larger than the distance (h3) between the ground of the construction side and an underground rock layer, h1=h3; if the designed depth (h2) of the cast-in-situ bored pile is smaller than the distance (h3) between the ground of the construction side and the underground rock layer, h1=h2; (2) drilling is conducted; and (3) hole cleaning and concrete pouring are conducted. The construction technique has the advantages that the technique design is reasonable, slurry supporting is not needed, the pollution to the environment is low, and large-diameter cast-in-situ bored pile construction can be conducted.