Aiming at the issues of low antenna configuration freedom and insufficient security in underwater visible light multiple-input multiple-output(MIMO) communication systems, a design for an underwater visible light MIMO transceiver assisted by odd-order orthogonal transformation based on chaotic encryption is proposed. Firstly, an odd-order orthogonal matrix generation algorithm is introduced to enhance the scalability of underwater visible light communication systems. Secondly, a dual chaotic encryption algorithm is employed to encrypt the transmitted data, improving the information transmission security of underwater visible light communication systems. Simulation results indicate that compared to baseline schemes, this approach offers superior reliability and security performance.