I tried it again, and it works fine now.
v4l2-ctl --list-formats-ext
i use command
gst-launch-1.0 v4l2src device=/dev/video0 ! video/x-raw, format=GRAY16_LE, width=1280, height=720 ! videoconvert ! xvimagesink
View format method
gst-inspect-1.0 v4l2src
