The effects of seawater temperature on the physiological performance of three Halimeda species were studied for a period of 28 d. Five treatments were established for Halimeda cylindracea, Halimeda opuntia and Halimeda lacunalis, in triplicate aquaria representing a factorial temperature with 24°C, 28°C, 32°C, 34°C and 36°C, respectively. The average Fv/Fm of these species ranged from 0.732 to 0.756 between 24°C and 32°C but declined sharply between 34°C (0.457±0.035) and 36°C (0.122±0.014). Calcification was highest at 28°C, with net calcification rates (Gnet) of 20.082±2.482 mg/(g·d), (12.825±1.623) mg/(g·d) and (6.411±1.029) mg/(g·d) for H. cylindracea, H. opuntia and H. lacunalis, respectively. Between 24°C and 32°C, the specific growth rate (SGR) of H. lacunalis (0.079–0.110%/d) was lower than that of H. cylindracea (0.652–1.644%/d) and H. opuntia (0.360–1.527%/d). Three Halimeda species gradually bleached at 36°C during the study period. Malondialdehyde (MDA) and proline levels in tissues of the three Halimeda were higher in 34–36°C than those in 24–32°C. The results indicate that seawater temperature with range of 24–32°C could benefit the growth and calcification of these Halimeda species, however, extreme temperatures above 34°C have negative impacts. The measured physiological parameters also revealed that H. cylindracea and H. opuntia displayed broader temperature tolerance than H. lacunalis.