To improve performance of TCP (transmission control protocol) Reno, a widely used TCP version, an improved TCP Reno named DAA-TCP is proposed. DAA-TCP (dual AMID-based active TCP) combines dual AIMD (additive-increase multiplicative-decrease) algorithms and adds an active congestion control manner, i.e., the congestion window may be decreased when some given conditions are satisfied before the congestion really occurs. DAA-TCP performances are investigated through simulations. Comparing with TCP Reno, the throughput may be improved; the retransmitted packets and the retransmit probability may be decreased. DAA-TCP can coexist with TCP Reno very friendly. In addition, DAA-TCP is obtained through a little modification from TCP Reno at the sender side, so DAA-TCP can be easily developed and the additional overheads are very low.