The objectives of this thesis were to study government policies on sugar-cane and sugar industry before and after the proclamation of Cane and Sugar Act 1984 and to study the economic impact on consumers and sugar producers after the enforcement of Cane and Sugar Act 1984. The study of economic impact from government policies was based on the basic concept of welfare economics i.e. consumer’s surplus and producer’s surplus. To obtain consumer’s surplus and producer’s surplus, the demand and supply equations had to be estimated first. The impact on consumers was calculated from the difference between consumer’s surplus at the constant domestic price and consumer’s surplus at the non-intervention price. The impact on producers was calculated from the difference between producer’s surplus at the actual price and producer’s surplus at the nom-intervention price. The impact of government policies on consumers and producers could be divided into 2 components: (1) Impact from raising sugar-cane price polices for sugar-cane farmers which resulted from packaging credit measures, control on production, import and export, tax measures, use of sugar as a raw material for export goods, cane and sugar fund, and the promotion of ethanol production; and (2) Impact from two-price policy which set the domestic sugar price higher than the world market price. The findings indicated that the impact of government policies after the Cane and Sugar Act 1984, during 1984 - 2003, the total consumer’s loss was 126,752 million Baht, while the producer’s gain was 352,726 million Baht. Most of impact from the government policies came from the raising sugar-cane price policy rather than the two-price policy.