From Shenzhen Airport:

Take subway Line11 at Airport Station and get off at Chegongmiao Station

then change subway Line1 to Exhibition & Convention Center Station.

http://www.szmc.net/cms/page?arg=bigmap

From Canton Fair (By train, takes about 3 hours):

Take subway or taxi to Guangzhou South Raiway Station (about 50-60 minutes)

then take train to Shenzhen North Raiway Station (about 30 minutes)

then take subway or taxi to convention center (about 30 minutes)

From Hong Kong Int'l Airport (By metro, takes about 2hour20mins):

Take Airport Express Line to Tsing Yi

then change Tung Chung Line to Nam Cheong

then change West Rail Line to Hung Hom

then change East Rail Line to Lok Ma Chau

then cross the border between HK and Mainland China

then take subway Line 4 to Exhibition & Convention Center Station

http://www.mtr.com.hk/en/customer/jp/index.php

From Hong Kong Int'l Airport (By taxi, takes about 1hour):

cost around USD50