Police said the 59-year-old man was found lying on the ground unconscious after 5pm at the hospital’s phase II main construction site.
An initial investigation showed that he was hit on the head by bricks.
The victim, who worked for the subcontractor, was rushed to United Christian Hospital where he was certified dead.
The Hospital Authority (HA) expressed sorrow over the case and offered condolences to his family.
The HA also told the project’s main contractor, China State Construction Engineering, to thoroughly investigate the cause of the incident and to submit a report as soon as possible.
“The main contractor has been urged to take the incident seriously and to adopt all necessary measures expeditiously to ensure site safety,” the authority said in a statement.
The HA said the company will also submit a report to the Labour Department, which sent officers to the scene to probe what happened and has launched its investigation.