Fonterra's chairman, John Wilson, will also be in Beijing but declined to give media interviews before leaving.
Mr Key will also be able to hold up the recent charges laid against Fonterra for its breaches of food safety regulations as evidence the Government has taken action.
Mr Key's office has so far refused to confirm whether he is likely to meet a representative from Oravida, the company at the centre of Justice Minister Judith Collins' conflict of interest issues. Many New Zealand companies have been invited to a function for New Zealand exporters and their Chinese clients.
Mr Key said the function in Beijing was to help promote those firms, their presence in China and to reinforce the Government's message about its processes to their Chinese clients.
He said the trip had the wider benefit of strengthening relations with China's leaders. He has met them four times in the past year.