For ancient China, the grain output per unit area should be an important symbol reflecting the development level of agricultural productivity. With regard to the estimation of rice yield per mu in Jiangnan in Song Dynasty, I tend to agree with most scholars at home and abroad [1], that is, the rice yield per mu in Jiangnan in Song Dynasty is 2 stones. This is by no means a coincidence, but the result given after comprehensive data analysis on the basis of the above two sections and tables. Moreover, it is far higher than the estimation of scholars so far, mainly using the new research results of econometrics as the conversion standard, and of course there are historical materials I have checked myself as evidence. For the core area around Taihu Lake basin, the yield of 2 stones per mu is a conservative figure, such as 2.5 stones in Suzhou, lakes and Xiuzhou. For Yanzhou, Wuzhou and Zhenjiang, that is, the hilly areas in the east and west, it seems to be high. It seems that the average yield per mu 1.5 stone in these areas is appropriate. Jiangdong polder area is also around 2 stones, so the average stone in the whole area is 2 stones. If item 12 in 15 listed in the above table is only the yield per mu at different sampling points, then item (1) and item (9) are the yield per mu of all cultivated land in Suzhou and about 75% of farmland in Shaoxing respectively, and item (15) can be regarded as the yield per mu in Jiaxing; It is not the result of "selecting sperm" or "collecting sperm", but the average yield per mu in western Zhejiang and eastern Zhejiang respectively. How to convert the average yield per mu of these two kinds of stones into today's quantity is different; At the same time, there are always different opinions on the estimation of grain yield per mu in Song Dynasty, so there are many people who calculate grain yield per mu in Song Dynasty with 200 to 450 Jin [2].