In response to the problem of the lack of theoretical formulae for calculating the wave overtopping impact force on a building behind the breakwater，combining with the two-dimensional physical model test results of a Mediterranean petroleum jetty expansion project，we propose four calculation methods of average wave pressure acting on the buildings behind the breakwater based on the pressure sensors' data，and compare and analyze the results of the total force sensor with the calculation results of various methods.The results show that the high kinetic energy of the wave overtopping drops causes the measurement results of individual pressure sensors to be higher than those of the total force sensor. When the test equipment is limited，the total wave pressure on the building can be approximately calculated by taking the average positive wave pressure value based on synchronous data from uniformly distributing pressure sensors.Different strategies for calculating the average wave pressure have an impact on the magnitude of the total horizontal force，the average wave pressure calculated based on all measurement data is more reasonable，and the total horizontal force obtained by adopting this calculation strategy is closest to the total force sensor's results.