The invention provides a micro fluid flow adjusting device based on air pressure drive, belongs to the field of micro fluids, and aims to solve the problems of low flow adjusting precision, low dynamic response speed and absence of capacity of measuring actual flow when an injection pump is adopted to adjust the flow in a micro fluid system. The micro fluid flow adjusting device adopts an air pressure drive mode, an air supply source supplies compressed air, outlet pressure is adjusted and set by a pressure reducing valve to obtain stable air supply pressure, the pressure is measured by a pressure sensor, a liquid in a liquid container passes a valve and a flow meter to enter a liquid micro-channel under the pushing of the air pressure, the actual liquid flow is measured by the flow meter and fed back to a microprocessor, the microprocessor outputs a control signal to change the working state of a micro valve, the liquid flow of the liquid micro-channel is adjusted, and closed-loop control of the flow is realized; further, a PID (proportion integration differentiation) control algorithm can be adopted, the adjusting precision and the dynamic response speed of the flow can be increased, and the liquid flow in the micro-channel can be adjusted accurately and rapidly.