Which shuttle bus from HKIA to Pentahotel kowloon? Can i take MTR to go there?

Well, there is no direct subway that can take you to the hotel directly.
So it's suggested to take bus no.101 at South Pacific Hotel, Morrison Hill Road, get off at King Tai Street, Prince Edward Road East. The duration is about 30 mins. And the ticket fare is 9.3 HKD per person.
After arriving, walk north around 330 yards. Then you can find your hotel easily. :-)

Hi hendry, thx for ur suggestion :) so from HKIA to South Pasific Hotel, i take MTR to go there? And after that i take busno 101?

Yes, MTR to South Pacific Hotel and then bus 101. The detailed metro route: airport express to HK Station first. Then walk to Central Station and take Island Line to Causeway Bay Station, Exit A. The whole way takes around 50 mins. The ticket fare is 100 HKD per person. After arriving, walk southwest around 280 yards and get to South Pacific Hotel.
Then you can take bus no. 101 to your hotel.