This paper presents a method that restrains a systematical behavior by a synchronistical measure and forces it to repeat a section of chaotic trajectory periodically, so that the high periodic chaotic signal can be obtained. The obtained signal not only keeps the typical features of the chaotic signal but also has the advantages of a periodic signal. The results of the simulation calculation, the experimental circuit and the experimental results about realizing the method on the basis of. Lorenz mode are given. The advantages of this method for applications in secret communication or covering information are discussed.