This paper analyzed the type of mini-type antenna, studied the miniaturization technique based on simulation in depth, and finally designed the high-performance micro-strip antenna. The advantages of micro-strip antenna are light-weight, compact size, relatively thin thickness, and so on. However, it still needs aggressive miniaturization to satisfy the requirements of encapsulation. Techniques for miniaturization of antenna mainly include a ground plane, double-layer patch, shorting pin or wall, lossless dielectric substrate and the spiral structure. The techniques of multi-layer and shorting wall can narrow down the resonant frequency and attain bandwidth enhancement. Nonetheless, they have a complicated structure. Thus, simulation researched the influence of the surrounding tissue in detail, the position relation of shorting pin and the feed point, the substrate parameters and the structure parameters of the spiral antenna on performance. At last, through the techniques of the shorting pin, high permittivity substrate and the spiral shape, two Archimedean micro-strip patch antennas were developed for wireless capsule endoscope. The antenna has the bandwidth of about 300 MHz, the minimum voltage standing-wave ratio of 1.14:1, and the diameter of 8.3 mm. Therefore, the antenna can offer excellent performance for transmitting image data.