Abstract: Emitting plane wave makes ultrasonic imaging enough fast so that it could detect variable blood signal in body, hence it becomes one of the most popular research interest. A new algorithm, multi-angle plane wave coherent compound imaging (MPWCCI) was realized to suppress side-lobe signal, improving the quality of ultrasonic image. Trading off frame rate and signal-noise-ratio (SNR), it could be used to image blood Power Doppler (PD). The contrast of B mode image could be up to 40 dB, and the frame rate to 1000Hz, using more than ten plane waves to compound. Test was accomplished in the slow-flow blood phantom, it shows that clutter signal could be eliminated and blood signal could be extracted effectively, and finally an image depicting hemodynamics was obtained. Result verifies that MPWCCI-PD has a fine sensitivity to slow flow. Furthermore, the effect of the ensemble size on image quality and temporal resolution was discussed. Calculating blood PDs in varying ensemble size data reveals that its frame rate exceeds that of conventional PD imaging, up to tens of Hertz, and the shorter the ensemble images are, the higher the temporal resolution and the better image, and vice versa. Higher temporal resolution is conducive to detecting fast blood flow and better sensitivity is good for the detection of small vessels. MPWCCI-PD may be helpful to imaging cases caused by angiocardiopathy, or brain small vessels.