The invention discloses an artificial speech bandwidth expansion method and device based on K-SVD. The method is characterized by including 1, training original wideband speech signals at the bandwidth expansion transmitting end, and acquiring a wideband speech dictionary, a narrowband speech dictionary and narrowband speech sparse matrix; 2, at the bandwidth expansion receiving end, performing bandwidth expansion on original narrowband speech signals through the wideband speech dictionary and the narrowband speech dictionary, and acquiring the expanded final wideband speech signals. By the aid of the method, the wideband speech quality is improved, the training time and prior knowledge usage are reduced greatly, the accuracy of the original narrowband speech sparse matrix is improved effectively, practicality is high, and the method can be applied to the field of speech communication widely.