In order to investigate the ground vibrations probably induced by the high speed rail when will pass through the Tainan Science Industrial Park, a proto-type bridge foundation supported on four large-diametered piles was built in the TSIP for the purpose of in-situ tests. A series of forced vibration tests on the pile foundation had been conducted. The test method, analysis procedure and results of test are briefly introduced in this paper. Besides, a numerical simulation by using the finite element program ABAQUS is conducted. Results obtained are in good agreement with the results of in-situ tests.