本文建構一個小型開放的經濟體系，價格具有僵固性的 DSGE 模型來探討提早釋出的關稅調降訊息所造成總體經濟面的影響。在政府簽訂貿易協定來降低關稅的訊息藉由媒體釋出時，同時民眾具理性預期的假設下，家計單位會因這樣的訊息而改變對未來的預期，在關稅還未實際調降時便改變行為決策。我們研究在不同的協商可能結果: (1)談判破裂，貿易協定未如預期簽訂。(2)談判成功，但貿易協定簽訂的結果比當初訊息所透露的降得更多或較少。(3)談判成功，並完全實現當初訊息的內容。(4)簽訂的時間高於預期，導致實行的時間延期。從結果中我們發現，提早釋出的關稅訊息會抑制民眾的消費和投資，在短期會立即造成需求面的負向衝擊。而降低關稅所帶來的市場活絡，會等到真正調降的時後才出現。所以越早釋出關稅調降的訊息，會造成經濟體系所需付出“等待政策實行的成本”越大。 / There is global trend of economic integration across the world by removing the trade barrier. While the free trade agreements normally include the tariff reduction, the negotiations of the agreement may take a long time, and in some cases, the negotiation may fail. Therefore, the tariff reduction’s effects on the economy can be different if it is realized as expectation or not. With a small open economy DSGE model, this paper examines the effects of news preannouncement on tariffs. With the assumption of rational expectation, households will change their expectation when the news of tariff decrement is preannounced. However, whether or not the news on tariffs can be realized as expectation will lead to different dynamics. In this study, we consider various plausible scenarios: (1) If negotiation fails, thus the news on tariff reduction is not realized (2) If negotiation succeeds, but the amount of actual decrement is more or less than people originally expected. (3) Negotiation succeeds and the content of news is fully realized. (4) Negotiation succeeds, but it takes more time than expected to be realized, thus the policy implementation is postponed. Our study reveals that the news preannouncement restrains consumption and investment before the negotiation is completed, and leads to a negative impact on the economy in the short run. The benefits of the tariff decrement appear if the policy is actually implemented as expected. However, the economy suffers more if the negotiation takes too much time after the news is released.