Any linear code can be used to construct a linear secret sharing scheme.In this paper,it is shown how to decide optimal linear codes(i.e.,with the biggest information rate)realizing a given access structure over finite fields.It amounts to solving a system of quadratic equations constructed from the given access structure and the corresponding adversary structure.The system becomes a linear system for binary codes.An algorithm is also given for finding the adversary structure for any given access structure. Any linear code can be used to construct a linear secret sharing scheme. In this paper, it is shown as how to decide optimal linear codes (ie, with the largest information rate) realizing a given access structure over finite fields. system of quadratic equations constructed from the given access structure and the corresponding adversary structure.The system becomes a linear system for binary codes. An algorithm is also given for finding the adversary structure for any given access structure.