Officers found 31 Chinese tourists and their guide still on board the bus after the driver took off about 6.30pm last night.
The Burmese woman, unidentified and aged about 55, was killed on impact not far from the landmark Thung Thong ice factory in Thepkasattri Road, Thalang.
About 600 metres along the road, the driver left his passengers and disappeared into the dusk. The group had been returning to a resort in Khao Lak from an outing at Coral island.
Pano Yogmon, owner of the Nong Film Karoake nearby, said: ''The woman crosses quite regularly to do her shopping on the other side of the road.
''I saw the bus coming and tried to call out to her, but she didn't hear me. The bus was going quite fast. It just kept going.''
The body of the woman was taken to Thalang Hospital. Thalang police are investigating.