Abstract: As we known, to simulate and measure the sound Transmission Loss (TL) in complex terrain environment such as lake, coastal port and mountainous shallow water face a lot of difficulties. We propose to measure the TL by using UUV platform which may bring with advantages of good maneuverability and efficiency. The data of lake experiments are handled with statistical methods. Meanwhile, the transmission models are simulated by BELLHOP to estimate the TL of experiments. When the source is placed in thermostat layer, the simulation agrees well with the measurement. However, when it is placed in negative gradient layer, the simulation is not corresponding to the measurement. By comparison, it is mainly because of the complex terrain and sediment of lake Bottom, which leads to difficulties of estimation on sound wave refraction and absorption. The experiments declared that field measurement have to be employed in this case, and the proposed method using UUV is proved to be more efficient and reliable.