The utility model discloses a drilling well for gas drainage, which comprises a sleeve section and a sieve tube section, wherein the sleeve section comprises a sleeve and a sleeve section well hole; the sieve tube section comprises a sieve tube and a sieve tube section well hole; the sieve tube is located in the sieve tube section well hole; the diameter of the sieve tube section well hole is larger than that of the sleeve section well hole; and a safe distance is kept between the outer wall of the sieve tube and the hole wall of the sieve tube section well hole. The method comprises the following steps: the sleeve section well hole is formed; the sleeve is placed in the sleeve section well hole and cementing a well; a drilling hole is formed through drilling under the sleeve section well hole and is expanded; the diameter of the drilling hole under the sleeve section well hole is expanded to be larger than the diameter of the sleeve section well hole, so that a sieve section well hole is formed; and the sieve tube is placed in the sieve section well hole and kept at a safe distance between the outer wall of the sieve tube and the hole wall of the sieve tube section well hole. According to the drilling well for gas drainage and the formation method, the sieve tube can retain a gas-outlet channel to an extent after being influenced by drainage, so as to ensure the smooth operation of gas drainage.