Fire damaged an exhibition zone under construction at the Central Phuket Floresta shopping mall on Saturday morning.
Police said the fire started at 10.15am and firefighters took about half-an-hour to control the blaze.
Workers were building a model of a volcano and the zone was scheduled to open to visitors in November.
Officials said the fire spread very fast as the models were mostly made of foam.
The cause of the fire has yet to be determined.