Startin g from January 1, 2016. China put a period to 30 years of One Child Policy, one of largest family planning program that in the human history. All Chinese couples are now allowing to have second child. However, the costly lesson has to be leaned. " For nearly four decades it had shaped relations between generations and between men and women to an extent never before seen". The period doesn't always mean an end but a new beginning. China have to deal with the Unintended Consequences caused by one child policy. One is a 1-2-4 family structure. which single child had four grandparents and two parents to care him, same while when he come to age, he has to shoulder the heavily responsibility of taking care four grandparents and two parents. Second major unintended consequences are the gender ratio, there are 18 women per 20 men because value men over women. Such unbalance gender ratio had "led to so-called "bare branches:" Chinese men who are not able to find a spouse or have to rely on "mail-order brides." The paper concludes that the OCP has come to an end, but the unintended consequences prevail." The first entry talks about how one child policy begin to affect behavior of single child, second entry talks about the how the one child policy end and the consequence single child has to bear. From the reader's understanding the consequence of one child policy are not only the gender ratio and family structure, but many other aspects from life. The path which new generation is walking now is settle by government's policy, but they are the one who have to finished it no matter what. The reader is more curious about the one child policy, the largest family planning in the human history what will it bring to China?.