A composite baseball bat includes a handle, which has a tapered portion formed on one end of the handle body thereof and gradually increased in diameter in direction away from the handle body, a spacer member formed of a soft material having a uniformly distributed predetermined thickness and covered on the periphery of the tapered portion of the handle, and a barrel, which is sleeved onto the handle, having a first opening ad a second opening respectively located on two distal ends thereof for the passing of the handle body of the handle and a tapered portion located on one end around the first opening and pressed on the spacer member against the tapered portion of the handle.