In order to research on DPA attack of RSA code chip, adopt corresponding attack method to attack encrypt program on AT89C52 single chip, a power consumption analysis testing platform was designed and constructed. With this platform, SEMD algorithm differential power analysis (DPA) attack experiment against the 8 bit simulated RSA running in a single chip was carried out. In the experiment, ZEMD attack algorithm became workless when the corresponding parts in the different power traces cannot be arranged. The reason of these phenomena was the random input of the plaintext.