Nowadays, most of the flow sensors have the disadvantages of small measuring range and poor flexibility, thus they are unable to adapt to larger scale and complex surface measurements. This paper proposed a type of flexible MEMS flow sensor with wide measuring range, which was based on the combination of working principles of thermal loss and thermal temperature difference. Polyimide (PI) was selected as the substrate material and platinum (Pt) thin film was used as the thermal sensing elements. The flexible MEMS flow sensor chip with the size of 9 mm×7 mm×30 μm was fabricated employing MEMS process based on metal sacrificial layer. The constant temperature difference measurement and control circuit based on double Wheatstone bridge was designed. The testing results show that the temperature coefficient of resistance (TCR) of the fabricated flow sensor was 0.2418%/℃, the input air speed measurement in the range of 0~36 m/s was realized, and the sensitivity in high-speed and low-speed ranges were 2 mV/(m/s) and 0.295 mV/(m/s) respectively. In addition, The designed circuits demonstrated excellent effect of temperature compensation for accurate measuring results. The proposed flow sensor has the features of wide measuring range, high accuracy, high sensitivity and easiness to implement temperature compensation, and is expected to be applied to the aerospace, national defense and other fields.