I wanna go from hong kong airport to shenzhen xinghua hotel near the science museum.

Hi, you cann take the direct bus from HK Airpport to Shenzhen Airport. It is in service from 08:20 to 21:00 hourly. The ticket fare is about CNY 220 per person. At Shenzhen Airport, you can walk to Airport East MTR Station to take subway Luobao Line and get off at Science Museum. The ticket fare is CNY 3. Walking out of the Exit B of Science MTR Station, you will find Xinghua Hotel.

Or you can take the airport shuttle bus upon your arrival at SHenzhen Airport and get off at the terminal station (Hualian Mansion). Then you will find the hotel easily. The shuttle bus may cost about CNY 20.
The whole journey may takes about 2 h.