The shape and microstructure of the fiber-optic liquid-level sensor head, which was made of two fusion-spliced multimode optical fibers, were experimentally studied by using scanning electron microscope (SEM) technology in order to optimize the performance characteristic of the fiber sensor head. The parabolic profile of the sensor head was found to be better and having length-width ratio from 1.2:1 to 1.3:1. Some other useful possibilities were proposed.