Five people were immediately killed by the leak on Sunday, while another five died later in hospital, said local authorities in a post on Weibo.
Officials are investigating the cause.
China has tightened industrial safety regulations following a chemical blast in Tianjin that killed 140 people.
Local authorities named the company responsible for Sunday's leak as Zouping County Shandong Fukai Stainless Steel Company.
They added that the seven survivors were in stable condition.
The Tianjin blast in August decimated a large part of the city's port. The high-profile incident reignited nationwide concerns about industrial safety and proximity of industrial areas to residential districts.
A gas leak at a stainless steel factory in the eastern Chinese province of Shandong has killed 10 people and poisoned seven others, authorities said.