The invention discloses a power distribution automation system security defense platform and method. The platform comprises a protocol dispatcher, a virtual operating environment, a conventional operating environment, a first power distribution automation system operating in the virtual operating environment, a second power distribution automation system operating in the conventional operating environment, a power distribution automation system terminal and a real-time database. By constructing a distribution automation safety access environment with a safety switching function and analyzing aterminal access protocol, possible dangerous attack behaviors are prevented, a safety defense mechanism is executed, and the safety access problem of the distribution automation terminal is solved.