The thesis explores three events of international trade, regarding an oligopolistic market. First, vertical integration reduces output firm’s marginal production cost. Thus a merge of upstream and downstream helps export industry in competition with a foreign rival via if the market is in Cournot duopoly. Nevertheless, triggering aggressive price competition, the integration can dampen export sector if the market is in a duopoly of Bertrand competition. Second, the collusion of upstream firms raises the marginal cost of producing final goods. The government should tight the enforcement of antitrust law to deter the collusions and hence promote the exports of final goods when the market is in quantitative competition. In contrast, antitrust law should be loosely enforced to alleviate price competition when the market is in price competition. Moreover, subsidizing (taxing) the upstream-firms’ production reduces (raises) the factor prices of downstream. The production subsidy of intermediate goods of producing final export can give export industry an advantage as what a direct export subsidy can.