In this paper we introduce a method and an implementation of blood flow imaging by means of backscattered Doppler ultrasound power. Compared with Color Flow Map technique based on autocorrelation, this technique is relatively angle independent, aliasing free and more sensitive to blood flow signal with noise background. We present the theory, experimental system and in-vitro experimental results. The realization of this technique means a new stage of color Doppler ultrasound imaging technique in our country is coming.