雖然GATT與世界貿易組織（WTO）不斷的推動貿易自由化，關稅與配額仍是許多國家常用的貿易保護工具。這些貿易保護的背後動機除了可以增加關稅收入與本產品市場佔有率之外，一般認為也肩負著部分產業政策的任務。透過保護，本國廠商以提術，增加全球的競爭力。因此本文主要目的乃欲探討在技術條件內生化之下，關稅與限額之等價性問題。 透過本文的分析，我們可以發現在技糐條偉內生下，課徵關稅時本國市場價何最低，其次為等量與等率限額，但在等值限額下，本市場創格之高低則需視需求而定。不過關稅與各種限額之等價均不能成立。此外由於存在策略性效果，因此關稅對本國廠商技術水準的提升最高，其次為等量限額，而等值與等率限額之效果則需視兩產量之變動比與產量比之大小而定。

　　　　　Although the GATT and WTO continuously promote free trade, tariff and some non-tariff barriers (NTBs) such as quotas and VERs are still adopted to protect domestic industries. The protection provide by tariffs and quotas can foster domestic technological upgrade as described by the infant industry concept. Therefore, if we take into account the technological upgrade effects, the arguments for the equivalence of tariffs and quotas, which prevail in the trade literature, may in fact not hold. In this paper, we endogenize firms' technology choices with respect to tariff or quota protection. It is found that the equivalence of tariffs and quotas do not exist. Though this study, we are able to pinpoint whether tariffs or quotas are more effective in brining about the technological upgrade for domestic firms.