In this study, Grey relational analysis technique proposed by J.L. Deng has been applied to spectrogram images of clinical mitral valve Doppler signals. A threshold level has been determined to plot maximum frequency envelope from denoised sonogram image using this technique. It is seen that, signal to noise ratio has been improved through Grey relational analysis technique. A software has been realized to support Doppler ultrasound device to diagnose vascular disease. This system has many advanteges that are reducing the computation time, ergonomic, cheapness.