In Korea, the aerial parts of the halophyte Salicornia europaea, known as hamcho, are used in salads in April–June and in oriental medicine in September–October In this study, with the aim of developing functional foods to aid blood circulation, hot water extract (HWE) and ethanol extract (EE) were prepared using hamcho harvested from the fields of Shinan, Jeonnam, Korea on 5th April (HWE-04, EE-04), 5th July (HWE-06, EE-06), 5th August (HWE-08, EE-08), 5th September (HWE-09, EE-09), and 5th October (HWE-10, EE-10), and their antioxidant and antithrombosis activities were evaluated. Among the HWEs, HWE-10 showed the highest concentration of total polyphenols and total flavonoids (22.4 and 17.6 mg/ml, respectively), and EE-09 had the highest concentration among the EEs (20.1 and 19.3 mg/ml, respectively). Among the HWEs and EEs, HWE-08 and EE-08 had the highest total sugar and reducing sugar content. In the antioxidation assay, HWE-10 and EE-09 showed strong reducing power, as well as DPPH, ABTS, and nitrite scavenging activities. The calculated RC50s of EE-09 against DPPH, ABTS, and nitrite were 578, 277, and 68.8 μg/ml, respectively. The antithrombosis activity assay revealed that HWE-04, HWE-06, EE-04, and EE-06 had anticoagulation activity against coagulation factors and that HWE-08, HWE-09, EE-08, and EE-09 expressed strong thrombin inhibitory activity, which was comparable to the antithrombosis activity of aspirin. In addition, EE-06 and HWE-08 exhibited strong aggregation inhibitory activities against human platelets. The results suggest that extract from hamcho harvested in particular periods and prepared using a defined solvent has strong potential as a novel food ingredient and an antioxidant and antithrombosis agent.