The invention discloses a ternary lithium power battery detection alarm device, which comprises a power supply conversion module used for converting an external input power supply; a photoelectric isolation module which is used for photoelectric isolation of communication signals; a main control module which is used for analyzing the operation input signal and outputting an operation result signal; a communication module which is used for sending an alarm signal to external equipment; a detection module which is used for detecting the gas concentration and temperature of the ternary lithium power battery; an alarm module which is used for giving a photoelectric alarm; and a alarm selection module which comprises an operation panel, an alarm output mode selection circuit, an alarm trigger concentration selection circuit, an alarm trigger temperature selection circuit and an alarm detection duration selection circuit, and is used for setting an alarm mode and an alarm value. Alarm valuesand alarm modes can be set according to different environments, external interference can be effectively reduced through different settings, and the false alarm rate is reduced. And a fault self-checking function is set, so that a user can discover device faults as soon as possible.