Zone Controller (ZC) was the key on-ground equipment in the Train Control System based on wireless communication. In a subway line, ZC was always set in the first level centralized station, which could be improved and optimized. Based on the introduction of ZC’s structure, function and interface, the paper analyzed the quantitative factors which impacted on the number of ZC layout number, provided the basic principles of ZC layout. Meanwhile, the calculation formula about ZC layout number was given in a subway line. Based on the first stage of Beijing Metro Line 10 project, the number of ZC layout was calculated by the given formula.