Step1 :
phone & pc connect the same wifi.
Step2 :
phone use usb cable to connect pc.
Step 3 :
$ adb devices
List of devices attached
0123456789ABCDEF device
Step 4 :
$ adb usb
restarting in USB mode
Step 5 :
$ adb tcpip 5555
restarting in TCP mode port: 5555
Step 6 :
$ adb shell ifconfig
wlan0 Link encap:UNSPEC
inet addr:192.168.43.74
............
Step 7 :
$ adb connect 192.168.43.74:5555
connected to 192.168.43.74:5555
Step 8 :
$ adb devices
List of devices attached
0123456789ABCDEF device
192.168.43.74:5555 device
Step 9 :
disconnect usb cable.
Step 10 :
$ adb devices
List of devices attached
192.168.43.74:5555 device
you can use adb shell to operate phone over wifi.
If you can't connect the phone, please reboot the phone then repeat above steps.