The invention relates to a skin effect-based sample surface coating nondestructive test method and system. The method comprises acting two ends of a sample to be detected through a frequency-variable AC signal, gradually increasing AC signal frequency, detecting resistance or voltage at the two ends of the sample to be detected, wherein the resistance or voltage is corresponding to AC signals with different frequencies, drawing a resistance-frequency curve or a voltage-frequency curve of the sample to be detected, analyzing a rule of change of the resistance change amounts of the sample to be detected or the voltage change amounts of two ends of the sample to be detected along with frequency change, and carrying out calculation or comparison with a standard sample to obtain thickness of the coating on the sample to be detected. The method and system realize integral measurement of the sample to be detected, has high detection sensitivity, realizes automatic measurement and has high detection efficiency. Through the skin effect, the surface defects of the material at high frequency are sensitive to a high frequency signal. Through change of AC signal frequency, coating surface defect and crack depth distribution information is acquired.