The explosion took place in the city of Fushun when two workers were making fireworks.
Two staff and four passersby were killed at the scene in the scenic zone of the "Liaoshen Campaign", state-run Xinhua news agency reported.
The "Liaoshen Campaign", an abbreviation of Liaoning-Shenyang Campaign, was one of the three major campaigns along with Huaihai Campaign and Pingjin Campaign launched by the People's Liberation Army (PLA) during the late stage of the Chinese Civil War.
Two re-enactment shows daily use more than 2,000 bullets and 600 mock-up shells.