A simple dynamic chemical etching device based on siphon principle is developed for fabrication of optical fiber probes which are commonly used in near-field optical microscopy. Probes with various shapes have been fabricated because the taper length and taper angle of the probe could be efficiently controlled through adjusting the speed and direction of water flux while etching. Compared with traditional static chemical etching, this method has the advantages such as reproducibility, controllability, convenience, lower cost, and it can make the probe surface smooth. Probes with apex diameter from 50 nm to 300 nm and taper angle from 16° to 65° have been achieved by this method. Moreover, double-taper probes with apex diameter less than 50 nm and taper anger larger than 125° could also be obtained by selecting appropriate water level difference. The mechanism of the chemical etching is discussed.