In order to achieve stimulating the multiple resonant point in the Lband,and use the sharp selectivity of the various resonant point to improve the antiinterference of the system,Opens circular aperture in the circular radiating patch, combines with two short circuit at the same time,so as through this method to design a multifrequency microstrip antenna in the Lband.The results from simulation experiment by HFSS which is a 3d electromagnetic simulation tool show that: when the angle of two short pieces is 90° orthogonal, and the distance from the center of the circle to the feed point is 25 mm, antenna generates three resonance frequency points as follows: 1.3 GHz, 1.53 GHz and 1.67 GHz;Frequency offset from low frequency to high frequency is up to 370 MHz.The multifrequency antenna is suitable for frequency hopping and multiple frequency communication system, and it, s height is only 1 mm, which can meet the demand of application of complanation.