The man who owned the explosives which had caused the blast last Sunday in Ningbo has been detained, state-run CGTN quoted local police as saying.
The police identified the suspect as a 33-year-old man from China's eastern Anhui Province. He was arrested in central Chinas Hunan province yesterday.
The suspect admitted that he told his family in Ningbo to dismantle and destroy the explosives to avoid being punished, it said.
The Sunday blast was China's worst industrial explosion in three years which also damaged nearby buildings and vehicles.
Rescuers were seen trying to pull the people out of the rubble from flats whose roofs were blown off.
Ningbo is one of China's major international cargo and container shipping ports.