The invention discloses a VR virtual construction system and a bidirectional real-time synchronization method thereof. A client terminal uploads a drawn 3D architectural drawing, a virtual application terminal renders the architectural drawing into a virtual scene model, the virtual scene model is fed back to the client terminal, a user checks the virtual scene model through the client terminal, the architectural drawing can be modified through a modification unit, then a rendering module modifies the virtual scene model in real time, the user synchronously modifies the architectural drawing according to the virtual scene model in real time, finally the drawing of the needed format is obtained through conversion of a conversion module, an information interaction terminal stores initial data, final data and intermediate modification data, so that the user can conveniently search in the later period, then the three-dimensional drawing is brought into virtual reality, a design scheme can be conveniently verified, material waste is avoided, project management is facilitated, and the user experience is better.