Is there any high-speed trains from Hong Kong Airport to Xiashan (chaoyang)?

I am sorry that there is no train service between them. You may fly to Chaoshan from HKIA (about 1 hour). The direct flights depart at 11:05 on Monday, Wednesday, and Friday. Upon arrival, take shuttle bus Shantou Xiashan Line to it directly. The buses depart at 10:10, 13:00, around 16：00, and around 20:00. The departure time of last two buses are up to the arrival time of flights. The trip takes about 3.5 hours, and the fare is CNY44.