A compact triband microstrip antenna for WLAN/WiMax application has been designed in this paper.The structure is similar to Tai Chi fish,and used coaxial feed which is near to the “fish′s eye”.There is a rectangular aperture on the patch which not only can improve the impedance matcheddegree of the antenna,but also can make the antenna have three resonancepoints that produced on the outer boundary of the patch.So this antenna can work on triband at the same time. The electromagnetic simulation software HFSS is used to simulate the antenna. The results show that the return loss of the antenna at the center frequency of 2.45 GHz,3.95 GHz and 5.25 GHz are 29.7 dB,29.2 dB and 27.4 dB respectively.The size of the antenna is about 0.24λ×0.18λ(λ is the wavelength of the frequency at 2.45 GHz in the free space),so it has the characteristics of miniaturization. The antenna has a small size, simple structure and good performance. So it has good application value.The center frequency of 2.45 GHz and 5.25 GHz can be used for WLAN band,and the 3.9 GHz can be used for WiMax band.