An ultrasound imaging device, comprising: a memory and a processor, the memory storing at least one program instruction, and the processor loading and executing the at least one program instruction to implement a method comprising the following steps: transmitting ultrasound pulses and receiving n echo signals in an interleaved transmission and reception manner in a blood flow imaging mode, wherein n is an integer greater than 1; acquiring a differential signal d(t) of the n echo signals; performing amplitude detection on the n echo signals to obtain an envelope of each echo signal, and acquiring a sum B(t) of the envelopes of the echo signals; calculating image gray intensity of the blood flow imaging mode according to d(t) and B(t), by updating the value of B(t) according to a magnitude relationship between B(t) and a preset threshold N thold, and calculating the image gray intensity of the blood flow imaging mode according to d(t) and the updated value of B ( t); acquiring B-mode ultrasound echo data; and performing scan conversion on the B-mode ultrasound echo data and the calculated image gray intensity of the blood flow imaging mode, and displaying an ultrasound image according to a conversion result, comprising the steps of: combining the B-mode ultrasound echo data and an image of the blood flow imaging mode, and displaying the combined ultrasound image; or displaying a B-mode ultrasound image according to the B-mode ultrasound echo data, and displaying a blood flow image according to the image gray intensity of the blood flow imaging mode. transmitting ultrasound pulses and receiving n echo signals in an interleaved transmission and reception manner in a blood flow imaging mode, wherein n is an integer greater than 1; acquiring a differential signal d(t) of the n echo signals; performing amplitude detection on the n echo signals to obtain an envelope of each echo signal, and acquiring a sum B(t) of the envelopes of the echo signals; calculating image gray intensity of the blood flow imaging mode according to d(t) and B(t), by updating the value of B(t) according to a magnitude relationship between B(t) and a preset threshold N thold, and calculating the image gray intensity of the blood flow imaging mode according to d(t) and the updated value of B ( t); acquiring B-mode ultrasound echo data; and performing scan conversion on the B-mode ultrasound echo data and the calculated image gray intensity of the blood flow imaging mode, and displaying an ultrasound image according to a conversion result, comprising the steps of: combining the B-mode ultrasound echo data and an image of the blood flow imaging mode, and displaying the combined ultrasound image; or displaying a B-mode ultrasound image according to the B-mode ultrasound echo data, and displaying a blood flow image according to the image gray intensity of the blood flow imaging mode. combining the B-mode ultrasound echo data and an image of the blood flow imaging mode, and displaying the combined ultrasound image; or displaying a B-mode ultrasound image according to the B-mode ultrasound echo data, and displaying a blood flow image according to the image gray intensity of the blood flow imaging mode.