Artemia salina cysts (capsulated and decapsulated) and larvae (instar I, II and III) were exposed to α-Fe2O3 nanoparticles (α-Fe2O3-NPs) to evaluate the effects on marine ecosystems. Hatchability, mortality and a number of ethological, morphological and biochemical parameters were selected as end-points to define the toxic responses. Results indicate that the hatchability of capsulated and decapsulated cysts was significantly decreased (p<0.01) following exposure to 600mg/L at 12, 18, 24 and 36h. Both increases of mortality and decreases of swimming speed were shown concentration-dependent manners. The LC50 values for instar II and III were 177.424 and 235.495mg/L, respectively (not calculable for instar I), the EC50 values for instar I, II and III were 259.956, 99.064 and 129.088mg/L, respectively. Instar II larvae show the greatest sensitive to α-Fe2O3-NPs, and followed by instar III, instar I, decapsulated cysts and capsulated cysts. Body lengths and individual dry weight of instar I, II and III larvae were decreased following exposure. α-Fe2O3-NPs attached onto the gills and body surface of larvae, resulting in irreversible damages. All of malondialdehyde content, total antioxidant capacity, reactive oxygen species and antioxidant enzymes activities were substantially increased in dose-dependent manners after exposure to α-Fe2O3-NPs suspensions, indicating that toxic effects were mediated by oxidative stress. Finally, the uptake result indicated that α-Fe2O3-NPs were ingested and distributed in the nephridial duct, primary body cavity and intestine of A. salina. Moreover, the uptake kinetics data show that the maximum α-Fe2O3-NPs content (8.818mg/g) was reached at 36h, and a steady state was reached after 60h. The combined results indicate that α-Fe2O3-NPs have the potential to affect aquatic life when released into the marine ecosystems.