The invention discloses a concentric 
pipe-following drilling tool. The concentric 
pipe-following drilling tool comprises a drilling tool body. The drilling tool body is coated with a protective layer. A preparing method of the protective layer includes the following steps that 1, 5.7 parts of modified 
polybutadiene resin, 2.3 parts of 
ethylene distearamide. 0.5 part of 
titanium dioxide, 1.1 parts of aluminum 
oxide, 1.3 parts of phenylcarbinol, 1.3 parts of 3-chloro-2-hydroxypropyltrimethylammonium 
chloride are taken and sufficiently stirred to be even, and a bottom-layer protective 
coating is obtained; 2, 6.7 parts of polyamino resin, 1.6 parts of 
methyl methacrylate, 1.2 parts of vinyl trimethoxy 
silane, 0.9 part of 
castor oil, 0.4 part of 
silicon dioxide and 1.2 parts of 
lime powder are taken and sufficiently stirred to be even, and a face-layer protective 
coating is obtained; 3, the bottom-layer protective 
coating is sprayed to the surface of the drilling tool body, cured and dried; 4, then the face-layer protective coating is sprayed, cured and dried. According to the concentric 
pipe-following drilling tool, the drilling tool body is coated with the protective layer, and the service life of the concentric pipe-following drilling tool can be prolonged.