Ether a go-go 1 (Eag1) channel is overexpressed in a variety of cancers but the therapeutic potential of Eag1 in osteosarcoma remains elusive. In this study, we constructed an Ad5-Eag1-shRNA vector and evaluated its efficiency for Eag1 knockdown and its effects on osteosarcoma. Our results showed that Ad5-Eag1-shRNA had high interference efficiency of Eag1 expression and suppressed osteosarcoma growth both in vitro and in vivo. To explore the molecular mechanism underlying tumor growth inhibition induced by Eag1 silencing, the intratumoral microvessel density (MVD) was assessed by CD31 staining and the expression of vascular endothelial growth factor (VEGF) was detected by Western blot analysis. We found that Eag1 silencing led to decreased angiogenesis and VEGF expression in the xenograft model of osteosarcoma. Finally, we detected a time-dependent decrease in VEGF expression and considerably reduced phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT) activation in osteosarcoma cells treated by Eag1 shRNA. Taken together, our results suggest that Eag1 silencing inhibits tumor growth and angiogenesis in osteosarcoma via the down regulation of VEGF/PI3K/AKT signaling.