The invention discloses a failure alarm circuit for an emergency stop solenoid valve loop of a diesel engine. The failure alarm circuit consists of a stop power supply, a stand-by power supply, a first current type relay normally-closed contact, a second current type relay normally open contact, a second current type relay normally-closed contact, a third current type relay normally open contact, a voltage type relay coil, a first current type relay coil, a second current type relay coil, a third current type relay coil, an emergency stop solenoid valve, a stand-by solenoid valve, an alarm power supply, a voltage type relay normally-closed contact, a first alarm lamp and a second alarm lamp. The failure alarm circuit is simple, and can respectively alarm and carry out timely self-protection for power failure caused by failure of the stop power supply and the faults of the emergency stop solenoid valve so as to ensure the normal work of the emergency stop solenoid valve loop. The invention further provides an alarm method for the failure alarm circuit for the emergency stop solenoid valve loop of the diesel engine, wherein alarms for different fault problems are given off through different alarm lamp lightening modes.