紐西蘭為臺灣重要的農產品進口國，根據2013年底生效的「紐西蘭與臺澎金馬個別關稅領域經濟合作協定」，臺灣逐年對紐西蘭在1,813項HS八碼農產品上實施零關稅以放寬敏感性農產品的保護措施。本文經由差異中之差異分析法估計適用優惠關稅的紐西蘭（實驗組）在各細項農產品上，與適用最惠國待遇稅率的對手國（對照組）之進口金額的平均處理效果，亦經由合成控制法對進口金額顯著有差異的農產品進行穩健性分析。結果顯示在乳製品、水果、調製食品及部分肉品上皆呈現零關稅的實施顯著影響進口金額平均處理效果。然而，正向平均處理效果的主因是紐西蘭長久為該農產品最主要的進口國，經由合成控制法的安慰劑測試亦可以發現臺灣若積極與該農產品上更具有生產效率的對手國如：美國、智利、義大利或澳大利亞簽訂優惠關稅貿易協定應該能創造更可觀的平均處理效果。

New Zealand is a crucial importer of Taiwanese agricultural products. The “Agreement between New Zealand and the Separate Customs Territory of Taiwan, Penghu, Kinmen, and Matsu on Economic Cooperation” (ANZTEC) eased protections for sensitive agricultural products by mandating the gradual lowering of tariffs on HS-8-digit agricultural products to zero. This paper estimates the average treatment effect (ATE) of import value between New Zealand (treatment group with preferential tariffs) and partner countries with the most-favored-nation (MFN) tariff rate (control group) through a difference-in-difference analysis (DID). A robustness test with the synthetic control method (SCM) was also applied. The results revealed a positive ATE after the tariff rate of dairy products, fruits, flavored foods, and some meat products became zero. However, the positive ATE can be primarily attributed to New Zealand's position as the largest importer of the aforementioned agricultural products. The placebo test demonstrates the potential of a more significant ATE if Taiwan signs PTAs with partner countries that are more endowed with certain competitive agricultural products, such as the United States, Chile, Italy, or Australia.