The invention discloses a bionic flow line resistance reducing drilling rod for coal rock stratum drilling under the complicated geologic condition. The bionic flow line resistance reducing drilling rod comprises a bionic concave connecting piece, a bionic hollow rod body and a bionic convex connecting piece. The surfaces of the bionic concave connecting piece, the bionic hollow rod body and the bionic convex connecting piece are convex bionic flow lines or concave bionic flow lines. The bionic flow lines are arranged to be multi-head variable lead helical structures. According to the rock strength of a construction site, based on the drilling method of the bionic flow line resistance reducing drilling rod for coal rock stratum drilling under the complicated geologic condition, the structure of the bionic flow line resistance reducing drilling rod and drilling process technical parameters are determined. By designing the bionic flow lines of the variable lead helical structure on the surface of the drilling rod, drilling resistance can be effectively reduced, the drilling efficiency and slagging efficiency are improved, drilling hole accidents caused by local heat accumulation in a drilled hole are prevented, and the drilling hole depth and drilling efficiency of a coal rock stratum under the complicated geologic condition are improved.