how to take mtr subway to shenzhen from hong kong airport

I think using the mtr to reach Shenzhen is inconvenient, so it is suggested to use mtr and bus to reach SZ.
You can take the airport shuttle bus line A21 to reach Hung Hom Station. Then you can take the East Rail Line to reach Lo Wu Station from Hung Hom Station. Then pass the border, you can reach the Luohu, Shenzhen.
The best method is to take the airport shuttle bus to reach SZ directly.