Abstract: The failure probability of electrical connectors accounts for a large proportion of the failure of all electronic components, and their failure will affect the reliability of the systems. In the present work, the typical failure modes, characteristics and causes of electrical connectors are summarized, and preventive measures are proposed. The open circuit is mainly due to the fracture of contacts or the cables in the end of contacts. The short circuit (breakdown) is mainly due to the proximity between two insulating parts or the entry of conductive foreign materials. The electrical parameter drift is mainly caused by excessive contact resistance between contacts, or the end of contacts and crimping cables. The root failure causes of electrical connectors are materials, design, processing, and service, etc. For preventing the failure of electrical connectors, more failure cases must be collected and analyzed.