PD (Power Delivery) technology has gradually become the standard equipment of recent electronic products. This paper proposes to use software methods instead of manual methods to improve efficiency for the failure inspection of I2C (Inter-Integrated Circuit) signals in PD chips. Through the mathematical analysis software MATLAB, find the correlation between the standard I2C signal and the unknown I2C input signal, and draw it into a graph. The regularity between the maximum value and the average value can be observed from the quantified data, on the other hand the difference can be directly observed from the graph, and the results of both can be confirmed to each other.