In recent years, with the rapid development of Guangdong-Hong Kong-Macao Greater Bay Area, the passenger flow between cities in the region has increased rapidly, and the requirements for transportation efficiency of intercity railways are getting higher and higher. Moving block and automatic turn-back technology is an important development direction of signal system to improve railway transportation efficiency, which can effectively shorten the tracking interval between trains and the turn-back interval of turn-back stations, thus improving the transportation capacity and efficiency of lines. At present, moving block technology and automatic turn-back have not been applied in intercity railway. According to the technical status of moving block and automatic turn-back, the feasibility of function optimization of existing intercity CTCS2+ATO train control system in Pearl River Delta is deeply analyzed in this paper, and the overall framework of realizing moving block and automatic turn-back in the intercity CTCS2+ATO train control system in Pearl River Delta is put forward. Finally, the working principle and realization of CCS block mode switching, driving permit calculation, automatic turn-back function optimization and turn-back process are introduced emphatically. The results show that it is feasible to realize moving block and automatic turn-back under the condition that the existing intercity CTCS2+ATO train control system in the Pearl River Delta is slightly changed, which is of great significance to improve the transportation efficiency of intercity railway lines in the Pearl River Delta. [ABSTRACT FROM AUTHOR]