High reliability dual power sources automatic switch circuit

A high reliability dual power sources automatic switch circuit is provided. The dual power sources automatic switch circuit includes a main power source circuit (41) and a backup power source circuit (42) installed respectively in a main circuit automatic switch zone (63) and a backup circuit automatic switch zone (64) which are isolated by a main isolation board (61) in the isolation apparatus (6). The main and backup power source circuits (41, 42) include manual switches (412, 422) installed in a manual switch zone (65) isolated by a sub-isolation board (62). The main power source circuit (41) includes a main switch (411) which includes multiple main switch elements (4111) coupled in series. The backup power source circuit (42) includes a backup switch (421) which includes multiple backup switch elements (4211) coupled in parallel. The invention also includes a power monitor module (5) to monitor abnormal conditions of the main and backup power source circuits (41, 42), and control the switch elements (4111, 4211) to perform power supply transfer.