This work is directed at developing a virtual instrument system as an accessorial diagnostic instrument for laryngeal diseases. Programmed with LabWindows/CVI, the system combines the voice acoustic analyzing function with the glottal image measuring function. The voice acoustic analyzing system can sample, store and replay vocal signals; can extract and analyze parameters, including fundamental frequency (F0), frequency perturbation quotient (FPQ), amplitude perturbation quotient(APQ), harmonics-to-noise ratio (HNR), jitter frequency (JF), Shimmer; and can do 3D sound graph analysis. The glottal image analyzing system can sample and store the image observed by the laryngostroboscope; can display any phase in one cycle of the vibration of the vocal cords or a slow and continuous movement of vibrating vocal cords; can snap and save the diagnostic frame of image; and can extract the parameters of the image such as the length and area of the glottis, the length and area of the vocal cords and the diseased part.