I have five public provided by ISP. I want to assign Public ip to PPOE users. I am using RouterOS 6.22.

Please help me!

You can try 1:1 mapping to the client's fixed private address:

http://wiki.mikrotik.com/wiki/Manual:IP ... :1_mapping

1:1 NAT will work if you want to manage firewall rules, etc from your main router. If you want to hand out the public IPs to a router downstream you have to do something different:

If you want to assign the public IP directly to them, create an address pool with the public IPs you want to hand out. In your PPP profile for PPPoE, select this pool.

When the user connects via PPPoE, it should directly assign them the public IP.