In food chain of terrestrial ecosystem, ants have roles as predator of other arthropods, eater of seed, nectar, plant and aphid secreation, and fragmenter of dead organic matter. This research wanted to know the ant biodiversities and dominant ant species at Bendosari Park ecosystem, Salatiga municipality. Sampling technique used pitfall-trap in 10 zones that every zone had different trees composition. Each zone put five pitfall-traps,for 2x12 hours that were collected at 06.00 and 18.00. Observation was done eight times, every two weeks. Research result got five sub families, 16 genera, 20 morfospecies and 1462 individu. Species richness index of ant at 06.00 and 18.00 were 2.48 and 2.35. Species eveneess index of ant at 06.00 and 18.00 were 0.76 and 0.54. Species biodiversity index of ant at 06.00 and 18.00 were 2.19 and 1.60. Species biodiversity index of ant that relatively high was found at zone 2 and relatively low was found at zone 6 eventhough there was not different from one zone to others.