Thomson scattering technique for investigation MW-discharge parameters in supersonic flows has been developed. This technique is very promising way for quantitative investigation of spatial and temporal distribution of electron density and temperature in middle and highly ionized plasmas. Applying this technique for investigations of MW discharge in supersonic flows is provided for the first time. High spatial resolution of this non-intrusive optical method permits to made the fist step in investigation of the spatial structure of MW discharge in flows with static pressure 50 - 70 Torr and Mach numbers 1,5 - 2. MW discharge is creating in a flow by impulse MW generator of X-range with output power 200 kW and pulse duration 1,5 μs. Impulse Ruby laser (6943 A) of 0.2 J pulse energy, 20 ns pulse duration and repetition frequency 0.5 Hz is used. Laser impulse is synchronized with that of MW generator and has the varying time-delay relatively the beginning of MW impulse. Time resolution of the developing method is about 100 ns, spatial resolution - about 0,5x0,5x0,5mm3. The scattered light is monitoring at the angle 135° and analyzing by diffraction spectrometer with comparatively high straight light level suppression. with highsensitive intensified CCD - camera. Analysis of several successful realizations of output signals shows, that spatial structure of MW discharge in such flows is very inhomogeneous and has high temporal instability. Our results confirm that MW discharge plasma under such conditions contains very thin channels with comparatively high electron density (up to 1016 cm-3), and electron temperature about 1,2 eV. The position and shape of these channels are strongly varying in each realization of discharge.