Encryption is an important method which is used to protect the information of an individual and enterprises and the secret of nations. Rijndael algorithm is the new advanced encryption standard, and has extensive application foreground because of its much merit. Modem encryption algorithms are based on keys. However, so far few of people research into the key schedule of rijndael algorithm and especially do research on the generation of its initial keys. This paper researches into the mapping of Logistic, makes use of a chaos algorithm to produce initial encryption keys because it can create chaos sequences of high randomicity. Further more, corresponding CPLD implementation is given.