Lola snail (Trochus niloticus) is one of the largest sea snails that live in coral reefsat Indo Pacific region and Indonesia including Saparua Island, the province of Moluccas. In a few recent years, the exploitation of lola snails has been increasing, so that the population of lola snails in nature decreases.. The yield of lola snail in Saparua Island and in the archipelagos of Banda from 1979 until 1992 showed a decrease from around 4 tons of dry shells to only around 0.25 tons. Furthermore, this research was aimed to estimate the size structure, age structure, and the sex ratio of lola snails population in Saparua Island, the regency of Central Moluccas. The sampling of lola snails used transects strip method.  Each transect was 100 m long and 2 m wide, which were divided into 10 segments of 10 m x 2 m. Transect was laid perpendicular to the coast line started from the lowest fall of the tides to the coast. The Bhattacharya method was applied for data analysis. The frequency distribution of shell diameter revealed that lola snails in Saparua Island consisted of nine size classes and two different age classes, which indicated that the population of lola snails in Saparua Island had two periods of spawning. Finally, from this research it could be concluded that the sex ratio of lola snail was 1:1.