The invention discloses a method for rewriting the bottom layer of a UE4 rendering engine and a communication mechanism thereof, belonging to the field of software. The rewriting method comprises: rewriting the mechanism of switching the display depth of the bottom layer of the UE4 engine, rewriting the mechanism of the bottom layer of the UE4 engine processing windows messages, Rewrite the underlying keyboard and mouse response events of the UE4 engine, rewrite the underlying mechanism of the UE4 engine to interact with other windows applications, rewrite the underlying window movement and scaling mechanism of the UE4 engine, rewrite the mechanism of the interaction between the UE4 engine and H5 applications, rewrite The timing trigger function at the bottom of the UE engine. By adopting the rewriting method of the above scheme, the development work can be facilitated without reducing the display effect, and the user experience can also be significantly improved. The invention also discloses a method for displaying a UE project in QT and a UE project. By rewriting the underlying mechanism of the UE4 engine, the UE4 rendering window can be embedded in QT to run and display, and the running frame rate and rendering effect are comparable to the UE client. .