The invention provides a mobile phone voice encryption structure and method based on a short-time Fourier algorithm and is used for realizing a real-time call and real-time voice encryption function. According to the circuit and method provided by the invention, a principle based on the short-time Fourier algorithm is adopted, real-time encryption can be carried out on a voice signal effectively, information security in a mobile communication process is ensured, and the structure and the method are characterized by high confidentiality, high synchronism, good applicability and low cost.