Submillimetre gaps caused by buttons, switches exist in the electronic device. IEC 61000‐4‐2 indicates that contact discharge method will be used if these floating metals could be touched in its normal use. Secondary discharge happens when conduct contact discharge on these floating metals. The influence of the secondary discharge on the repeatability of contact discharge method using experimental method is analysed. At same applied voltage, the secondary discharge current varies largely, causing bad repeatability. The time lag is the main parameter that influences the secondary discharge greatly. The time lag distribution is also analysed.