For the evolutionary algorithm, the representation of the electronic circuit has two methods, one kind is code with the electronic circuit solution space, the other is code with the problem space. How weighs one representation quality may think the following questions? The first is the code method should as far as possible complete, it is say for the significance solution circuit or the optimize solution obtains in the problem space may represented by this code method. The second is the code method should speeds up the convergence speed of the algorithm search. The hardware representation methods mainly include binary bit string representation, tree representation, Cartesian Genetic Programming representation and other representations. In this paper, we will introduce the representations of the binary bit string and Cartesian Genetic Programming in detail, then give some examples of the two representations.