Based on the traditional falling ball method to measure the liquid viscosity coefficient，combined with Millikan oil drop experiment，the oil drop in the air is simulated as a small ball moving in the liquid，so that the idea of measuring the liquid viscosity coefficient by falling ball method can be applied to the measurement of air viscosity coefficient．The CCD imaging system is used to capture the state of oil droplets and use intelligent phones to record their movement process．The“ Tracker ”software is used to collect relevant physical quantities，and finally the air viscosity coefficient is calculated．