Abstract: “The Second North Paradox”is a problem description of some contradictory conclusions existing among economic growth, institutional changes and transaction costs, which was proposed by domestic scholars in the beginning of this century. If the deep relation between the total transaction costs and the cost of a single transaction is clarified, “the Second North Paradox”does not exist at all. In addition, the following conclusions can be drawn: firstly, the standard to measure the institutional changes should be the level of a single transaction cost, rather than the total transaction costs; secondly, the total transaction costs can be divided into two parts: the institutional costs and the sum of market transaction costs under the established institutional system; besides, the rise in the total transaction costs helps to decrease the cost of a single transaction cost; thirdly, the proportion of the total transaction costs to GDP will not rise infinitely, meanwhile, the decrease of single transaction costs and the rise of the total transaction costs will co-exist only within a certain range.

Key words: 诺斯第二悖论；单笔交易费用；总量交易费用；制度变迁