This is the body of a man who was decapitated in 1927. Without further information on the source of the photograph, it is impossible to say who was executed (communist activist, unionist, etc.) and by whom (local warlord, nationalist troops). This was part of trail of violence that accompanied the takeover of Shanghai in February-April 1927. One thing is certain: the death penalty by decapitation had been abolished much earlier. This would appear as a summary execution to scare the population. All on-lookers seem to be Chinese (shoes).