You will need to set up and update the geoip database before it works.
iptables -I INPUT -m geoip -p tcp --dport ### --src-cc CN -j ACCEPT iptables -A PREROUTING -p tcp --dport ### --src-cc ! CN -j DNAT --to-destination 1.1.1.1:333
replace 1.1.1.1 with your IP and 333 with whatever port you want.
Here is a tutorial to help you out: http://xmodulo.com/block-network-traffic-by-country-linux.html
You will need to periodically update the databases as sometimes ip addresses change owners and countries.