The  two  main issues discussed in this article  are as follows:(1)Jiangnan(the  Yangzi Delta)saw  a very slow  population  growth  in the early and the  mid-Qing  times(1644-1850).The  growth rete was strikingly low--only  about 0.3  percent a  year  in  such a  long  period  of two centuries，which was not much   lower than those of most parts of China or of China  as a  whole  at the same period，but  even considerably  lower than those of Jiangnan  itself  in  the  preceding  period  of  Ming;(2)the slow  growth of population  was the result of a  positive population control in Jiangnan,leading to a “harmony” or equivalence between economic growth and population  growth  and aiming  at  that the  people could keep a  higher standard  of  living that they had enjoined.In  this  sense,we  can say  that this demographic behavior is quite rational or even “modern”.These findings challenge  the conventional  wisdom，denying that there was anything like “population  explosions” or “no controlling  population  increase” in  early and mid-Qing  Jiangnan.