The remote transmission of tumor ultrasound images is an important link in telemedicine. Based on the Galois field (GF), this paper proposes an encryption algorithm that ensures the security of tumor ultrasound images (TUIs) during the transmission. First, the grayscale image of the TUI was generated by the secure hash algorithm 1 (SHA-1) algorithm, and the resulting hash value was taken as the medical record summary, which was used to monitor the transmission of the TUI. Second, the 2D ciphertext image was expanded into 1D vectors, and the TUI was encrypted with the non-repetitive scrambling algorithm, coupled with two diffusion algorithms. The simulation results show that the coupled algorithm can ensure the safety of the TUIs in remote transmission.