Focused on the problem that the protection photoelectric conversion device alarm information can not be monitored on-line, the alarm acquisition system based on the Raspberry Pi is proposed for the protection photoelectric conversion device. The automatical analyzing and judging flow is proposed for the protection channel fault, which is based on the comprehensive analysis of the alarm information about protection photoelectric conversion device and professional network management system of the transmission equipment. Via the proposed on-line monitoring system and the fault automatic analysis and judgement procedure, the step of spot investigation of the alarm information for the protection photoelectric conversion device is saved, and the procedure of coordination and analysis by the two kinds of experts, including the communication and protection ones, is simplified. It has positive significance for detecting and locating the protection channel fault section early, improving the intelligent level of the protection channel fault searching and processing.