SPS Measures Impact on the Trade Model: a Case Study of China's By adopting the partial equilibrium and compliance cost, this paper analyzes four models produced by SPS measures impact on trade. They are: a country discriminated by another, a trader discriminated by all importers, a large trader discriminated by all importers, and nondiscrimination. By demonstrating China's agricultural trade, the paper concludes that the compliance cost is maximized when small countries are discriminated by all importers, and is minimized when large countries are in a nondiscrimination situation. Accordingly, international standards are the best reference to reduce compliance cost and transaction cost.