The　output　performance　of　the　tetra-lateral　two-dimensional　position　sensitive　detector　(PSD)　was　experimentally　investigated　while　only　two　of　its　four　output　electrodes　worked　alternately.　Then　the　finite　element　method　was　used　to　simulate　and　calculate,　and　the　computational　results　were　agreement　with　the　experimental　data.　As　compared,　a　square　one-dimensional　PSD　was　simulated　and　calculated　also.　The　conclusions　are　of　practically　significant　for　PSD　design　and　application.