what the best public transportation to get to hongkong?

There is no Ouzhuang subway station; you must refer to Quzhuang Subway station, right?
From Quzhuang Station, you can take the subway line 6 to Yantang Station, where you can transfer to Line 3 to East Railway Station. From the railway station, you can take the train to HK, and the travel time is about 2 hours.