This paper explores possible impacts of joining WTO and related economic deregulations on Taiwan in the process of economic development. In order to participate in WTO, important issues and required adjustments faced by Taiwan include the following: Public consensus, down-payment clause, reduction of tariff rates, environment standard, government subsidies and purchases, as well as political uncertainty between cross straits. The impacts on individual industrial sectors are not the same. The primary (agriculture) sector would receive serious impacts, the adjustment policy should focus on how to raise farmers' income. The scondary (manufacturing) sector would have least even positive effects in the long run. The influence on the third (service) sector is ambiguous, deregulation of domestic market will cause more competition and cooperation with foreigh firms, which would increase the efficiency and skill of domestic firms.