This paper extends the existing theory on the equivalence of import tariff and quota. If the equivalence is defined on the domestic price level (weak equivalence), then either the zero conjectural variation for domestic country or a perfectly competitive market will be sufficient to support this equivalence. If the equivalence is defined both on the same domestic price level as well as tariff rate (strong equivalence), then the conditions are that either domestic country acts as a Cournot competitor and foreign country is a price taker, or both domestic and foreign country are price takers. An empirical spatial-equilibrium trade model is constructed to simulate the impacts of import tariff and quota. Using Taiwan??s rice import as an example, the empirical results show that if Taiwan switches from the quota system to tariff system, the domestic rice price as well as total social welfare can be increased given the same import volume.

本文对现有的进口关税与配额等值理论进行了扩展。如果等价是在国内价格水平上定义的(弱等价)，那么国内零假设变异或完全竞争市场将足以支持这种等价。如果等价是在相同的国内价格水平和关税水平上定义的(强等价)，那么条件是要么本国作为竞争对手，而外国是价格接受者，要么本国和外国都是价格接受者。建立了一个经验的空间均衡贸易模型来模拟进口关税和配额的影响。以台湾稻米进口为例，实证结果显示，在同等进口量下，若台湾由配额制转为关税制，国内稻米价格及社会福利均可提高。