The manufacture of micro-nano three-dimensional (3D) probe is a key factor for Micro-nano Coordinating Measuring Machine (Micro-nano CMM) to achieve the precise measurement. This paper proposes a method to fabricate a microball from an optical fibre using a fibre fusion splicer, which is used for Micro-nano CMM to measure miniature workpieces. Utilizing fused optical fibre tapering and choosing proper melting parameters, a microball with diameter of about 100μm and with roundness of less than 2μm could be fabricated. The offset distance between the microball centre and fibre stylus central line due to the gravity effect could be less than 1μm. This approach not only greatly reduces the time for the preparation of the probe, but also extends micro-nano CMM’s capability of measuring miniature workpieces.