Chlorella pyrenoidosaChick and Photosynthetic Bacteria were immobilized by sodium alginate and calcium chloride for aquaculture wastewater purification, and the purification capacity was investigated. The conditions of its immobilization were studied by orthogonal experiments.The results showed that algae-bacterium immobilized balls which were embedded by 2% sodium alginate and cross-linked for 24 h by 6% calcium chloride improved orthophosphate and ammonia-nitrogen removal efficiency, which respectively reached 84% and 95% at 24℃. It was higher than immobilization algae and bacterium separately (P<0.05) for orthophosphate during the periods of first-forth days and for ammonia nitrogen during the periods of fifth-eighth days. The studies indicate that the purification capacity of algae and bacterium can be improved significantly for aquaculture waste water by using algae-bacteria combination and to be fixed reasonably. Applying algae-bacterium immobilized balls has better effect than adopting algae and bacterium separately in purification efficiency of aquaculture wastewater.