The YF-100 is a Chinese liquid rocket engine burning LOX and kerosene in an oxidizer-rich staged combustion cycle. Development of the engine began in the 2000s, along with its sibling, the smaller YF-115, which would power the LM-6 and LM-7 upper stages. Testing was directed by the China National Space Administration (CNSA) commencing in 2005. Development works are mainly carried out by the Xi'an Aerospace Propulsion Institute. The engine had its first 300 seconds test fire on November 2007.