寶安縣
Line 6 had a planning history of over 20 years with major design changes along the way. In the 1994 "Shenzhen Urban Passenger Transport Master Plan", Line 6 was a metro line proposed to start from Bao'an International Airport to Songgang, with a line length of about . It was envisioned as an extension of the still under planning Line 1 to connect the industrial and manufacturing centers of the then Bao'an County with the Bao'an Airport and the Special Economic Zones of Shenzhen. At the time Bao'an was not part of the Shenzhen Special Economic Zone, the purpose of Line 6 was to promote the development into Bao'an's western corridor and the northern industrial hinterland by extending the reach of the Shenzhen Metro.