The methods that are used to produce microwaves can affect the strength and stability of plasma spectral signal in laser-induced breakdown spectroscopy (LIBS). Leaf vegetables that contain cadmium (Cd) at mass fraction of 1.5×10-5 are used as the subjects of this study. The influences of microwave probe with four shapes, such as the single-needle, double-needle, single-ring, and double-rings microwave probes, are studied. The three microwave loading positions, which include the front, middle, and end of the probes, are also investigated. The form of microwave function in the microwave assisted LIBS (MA-LIBS) experiment is optimized to achieve better auxiliary enhancement effect. After analyzing the spectral lines of the MA-LIBS, we find that the plasma spectral signal of Cd element is increased by 2.58 times, whereas Si and P elements is increased by 2.70 and 3.08 times, respectively. Suitable microwave probe shapes and loading positions can improve the effects of microwave-assisted enhancement, which further improves the performance of the LIBS technology in the application fields.