Ren Xifen had a "grim, tear-filled reunion" with the siblings -- a 13-year-old boy and his younger sisters -- who died after drinking pesticide, Xinhua news agency said.
"I did not shoulder my responsibility for them," 32-year-old Ren said, as she returned Friday to see their bodies at the family home in Bijie, in the remote southwestern province of Guizhou.
"I had to come back for a final look at them," she added.
They died soon after and police believe it was suicide, in a case highlighting the plight of rural children left behind by their parents who travel to the cities in search of work.
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Ren told Xinhua she had not contacted her children since leaving home in March last year to work at a toy factory in the southern province of Guangdong.
She left after a "long and bitter dispute" with her husband Zhang Fangqi, the report said, adding that the father left the village in March, leaving his children behind.
She also described her only son as "very lovable" and said he was diligent.
"I am illiterate and cannot even write my own name. I wanted them to perform well in school, unlike me, living a hard life," she said.
The incident sparked widespread public sympathy and prompted Chinese Premier Li Keqiang on Friday to call for "an end to such tragedies", vowing to punish officials who are lax in providing due assistance to families with similar problems.
An investigation had been launched and several officials have been suspended or removed from their positions.
The country has more than 60 million "left behind children" and nearly 3.4 percent of them live by themselves, Xinhua said, quoting a 2013 report by the All-China Women's Federation.
"In the case of Ren's family, no grandparents were still alive to watch the children," the news agency said.