stunt double       
noun [ C ] uk/ˈstʌnt ˌdʌb.əl/ us/ˈstʌnt ˌdʌb.əl/
 特技替身演员
someone who performs stunts (= exciting dangerous actions) instead of an actor in a film or television programme
  They put in stunt doubles for the climactic fight scene. 他们在高潮的打斗场面中安排了特技替身。 
 I later found out that my stunt double had refused to do the jump because of the potential danger. 我后来发现,我的特技替身拒绝跳跃,因为有潜在的危险。 
 - More examples
 - He didn't use a stunt double for those boxing scenes.
 - Soon special effects will take over and the real surfers will be reduced to the status of stunt doubles.
 - Green screens and special effects have taken jobs from stunt doubles, but technology has made their work safer.