Being a member of the WTO from 2002, Taiwan should phase out the import tariffs of meat. And it impacts on domestic livestock and poultry industry. This study applies the econometric model to analysis domestic livestock and poultry market structure, and uses the Gauss-Seidel method to estimate its impact effect by the annual data of Taiwan poultry quantities, price and related variables from 1981 through 2004. From the empirical results, if other things being equal on Taiwan's livestock and poultry industry in 2004, we could know the case that meat's tariff remain 10%, the farm prices of hogs would decrease 0.32 dollars per kilogram or 0.67%; quantities supplied will be the same as that in 2004; retail price would decrease 0.31%; quantities demanded would increase 1.22%; pork import would increase 1.69% and prices of mixed feed for hogs decrease 0.139 dollars per kilogram. The farm prices of both broiler and colorful broiler would decrease 1.61% and 2.98%; the quantities of both broiler and colorful broiler would decrease 1.91% and 1.32%; retail price decrease 2.2% and 2.8%; quantities demand increase 0.07% and 3.48%; broiler import increase 19.19%; prices of mixed Feed for broiler decrease 0.0209 dollars per kilogram. If the meat's tariff goes down 5%, the profit in livestock industry would decline to little, the producers would loss 5-6 dollars per kilogram and this would force Taiwan poultry industry to adjust.