Can you explain a bit more what you want?

Hello,

Exist Nutanix AHV cluster with default web browser management 192.168.168.100 in eth0 and eth1(LACP), customer want to add one more 172.166.166.100 in NIC port eth2 for another department web browser management, could setup? 

Ahh so with webbrowser management you don't mean Prism? But some other application? 

Create a new virtual switch in Prism Element (Settings → Network Configuration → Virtual Switch → + Create VS). Make sure you add the unused interface (eth2 in your case) to the virtual switch and complete the wizard. 

When the new virtual switch is created attach a network to it: (Settings → Network Configuration → Subnets → + Create Subnet). Make sure you choose the new virtual switch and vlan attached to it. 

Update: If you mean extra ip address on different interfaces only for Prism then that is not possible.  You can, however, separate backplane traffic (intra cluster traffic) on different interfaces though.