We performed a long range acoustic propagation experiment in the South China Sea (SCS) in November 2004. The environment of the experiment was with an isothermal sound speed profile, where influence of water volume fluctuation was small, meaning that bottom parameters can be well estimated from acoustic signals. We inverted the acoustic parameters of sediment by using a hybrid inversion scheme that combines the matched field processing inversion with Hamilton sediment empirical relationship and transmission loss data. The numerical results show excellent agreement with the experiment data, indicating validity of the inverted parameters.