The feeding of the micro-strip patch is flexible and complex, especially side feeding. In this paper, a single micro-strip patch antenna with a center frequency of 2.45GHZ is taken as an example to explore the performance of the slotted feed and non-slotted feed and verified in HFSS15.0. Combined with HFSS15.0 software simulation and theoretical calculation, the corresponding conclusions can be obtained. The theoretical value and simulation results will be shown that: the required 1/4 converter sizes of the non-slotted side feed and slotted side feed are different. By contrasting with sizes of two feeding modes, electrical size of the slotted feed is smaller. It can be known that all performances of the slotted feed are more superior.