The 64-year-old was stabbed in the stomach whilst on stage during an event in China.
“He was stabbed in the tummy area and also got a cut on his right hand,” Yam's manager Lester Mo revealed.
Video of the incident has appeared on Chinese social media platform, Weibo.
A police statement says the attacker has not been identified and that the actor may have been a victim of mistaken identity.
Angelina has high praise for Simon who has appeared in a whopping 125 movies and 40 television series.
Speaking about her favourite scene to shoot in Lara Croft Tomb Raider: The Cradle of Life, Jolie said: “I loved the fight with Simon Yam.”