Abstract: In order to achieve small area implementation of encryption in resource-constrained smart cards, we studied the hardware optimal implementation of electronic product code block cipher(EPCBC) encryption algorithm. Firstly, each operation is accomplished only once, and the main program calls the 32 times to complete the encryption. Secondly, the same register is used in the S-box and key transformation so that the number of required registers is reduced. Thirdly, the cipher round operation and key update are put in the same module. Through field programmable gate array(FPGA) the experimental results show that the implementation area of EPCBC is greatly reduced, the optimization efficiency rate reaches 56%, and the encryption performance is not decreased so as to provide practical solutions for resource-constrained cryptographic smart cards.