Center structure of excavator drill rod

The invention relates to a center structure of an excavator drill rod. The excavator drill rod comprises n sections of main rods and a section of a core rod, wherein each section of the main rods comprises a drill rod and a driving pipe connected with each other; each section of the driving pipes is provided with a driving pipe inner key in the length direction thereof; strip outer keys as long as the drill rods are arranged outside the second to nth drill rods and the core rod in the length direction; and drill rod-centered key bar structures are welded in the connection right-angled positions of the strip outer keys and the drill rods. As the drill rod-centered key bar structures are welded in the connection right-angled positions of the strip outer keys and the drill rods, when the driving pipes drive the next sections of the drill rods, the next sections of the drill rods naturally slide to the center positions of the driving pipes under the effect of welding the drill rod-centered key bar structures in the connection right-angled positions of the strip outer keys and the drill rods, the better coaxiality of the driving pipes and the drill rods is kept, and uneven stress of the drill rods due to the working deviation of the key bars caused by the eccentricity of the driving pipes is prevented.