The invention belongs to the field of precision testing of machine tool functional parts, and relates to a numerical control servo tool holder precision detecting device and a using method thereof. The detecting device comprises a tool holder test bench, a detecting platform, a parallelism and offset detecting frame, and horizontal iron; the tool holder test bench is fixed on the horizontal iron;the detecting platform is fixed on the horizontal iron and faces the tool holder test bench; and the parallelism and offset detecting frame is placed on the detecting platform. The use method of the detecting device includes the following steps: installing a tool holder to be tested and the detecting platform; installing the following parts below a guide block of the parallelism and offset detecting frame; applying the pre-tightening force; installing parts above the guide block in the parallelism detecting direction; coarsely and precisely adjusting the parallelism; performing axial parallelism detecting, radial parallelism detecting and offset detecting. The invention can accurately and quantitatively detect the parallelism and offset of the tool mounting surfaces of different types of numerical control horizontal servo tool holders at the same time, can quantify the adjustment amount of a debugging process, can facilitate the user to quickly complete adjustment of the detecting device, and is practical.