“…Some researchers like Frank [1], Poul [2], Newman [3], Ricardo [4], Chen [5] and etc have done lots of work on the Green function. Researchers like Liu [6], Dai [7], Ma [8], Zhou [9], Zhou [10] and etc also have gotten their findings. In 2010, French scholar Ricardo [4] published his research results of the Green function, which pointed out that if using infinite series or integral to represent the two-dimensional frequency domain Green function with free surface, it has an ambiguous theory discourse, a huge mount of computation and some inconvenience in practical.…”