Appropriate wave generation methods,wave equations and mesh size should be provided as setting up an exact numerical wave tank.Based on FLUENT model,we adopt three wave generation methods,including the source term method,pushing plate method，boundary velocity method to set up numerical tanks for wave simulation of different mesh size and different wave steepness.Combining with the corresponding wave theory,we comparing the effects of numerical first-order linear wave,second-order Stokes wave and third-order Stokes wave by three wave generation methods,and obtain the characteristics of numerical wave propagation,the appropriate grid scale and the influence of wave steepness on the numerical wave effect.The results show that the numerical wave height using the source term method attenuates relative sharply,it is the most sensitive to the change of mesh size.The simulation results using the push plate method is the most exact.The computation efficiency for the velocity boundary wave making method is the highest.The wave height attenuation speed is the slowest.The wave propagation in the numerical flume has the nonlinear effect.The nonlinear the influence during transportation can be observed,and it causes the nonlinear deformation of the wave surface even if the making wave is linear.