This paper makes a preliminary study on the visions and trends of the 6G mobile communication system. It believes that the breakthrough of basic information theory is the starting point of 6G development

and the development direction is to serve the individualized needs of human sustainable development. The paper preliminarily outlines the 6G’s total vision and the vision of each dimension. Then

we expand the actors from the three dimensions of "human-network-thing" to four dimensions of "human-network-object-environment"

in the network. It is believed that future 6G will change the "environment" of the broad concept of human beings. We summarize the four new forms of 6G networks: interconnection of whomever

wherever

whenever and wkam. The development trend of 6G network performance should follow TRUST principle

including more than Tbit/s level bandwidth

extreme Reliability

Ubiquitous connectivity

Sub-millisecond delay

Terahertz spectrum

visible light communication and spectrum currently in use（including but not limited）. Finally

the paper expounds the representative key theoretical

technical and academic research results from different layer of the 6G network.