The invention discloses a three-dimensional data rendering system for VR and a method thereof. The system comprises a server side and a client side. The server side renders a reality scene and transmits the reality scene to a display device of the client side for display. The client side comprises a head-mounted display device and a mobile client side. The server side comprises a virtual reality engine. The mobile client side is mounted on a smart mobile device held by a user. The smart mobile device interacts with the server side through wireless communication. The smart mobile device is an Android mobile phone. Through combination of the method, the defects that in the prior art, the display delay of an application is very high and a display rendering mechanism does not apply to the VR are avoided.