Based on the CEPA between the Hong Kong SAR and Chinese mainland signed in 2003, this study examines the impact of progressive trade agreements on trade statistical differences. Three findings emerge. First, the positive relationship between import tariffs and statistical differences still exists, but the CEPA significantly reduces statistical differences by adjusting for trade volume rather than unit value. Second, considering statistical differences, the effect of duty cuts for similar products as a group is greater than that of stepwise duty cuts. Third, the implementation of more restrictive rules of origin may effectively reduce statistical differences, but it is also likely that this reduction is due to the re-export from third countries via Hong Kong.