The invention discloses an emergency shutdown electromagnetic valve loop failure switching and alarming circuit of a diesel engine and a method thereof. The circuit comprises an emergency shutdown electromagnetic valve loop which is connected with an undercurrent detection current relay and an overcurrent detection current relay in series, an emergency shutdown standby electromagnetic valve loop,an emergency shutdown electromagnetic valve overcurrent switching control loop, an emergency shutdown electromagnetic valve undercurrent switching control loop, a relay used for detecting the failureof a shutdown power source and switching the shutdown power source to a standby power source for power supply, and an alarm loop under the situations of power loss of the shutdown power source, an emergency shutdown electromagnetic valve overcurrent and an emergency shutdown electromagnetic valve undercurrent; and the method thereof comprises the steps that when the shutdown power source is in failure, the shutdown power source is directly switched to the standby power source for power supply, during an emergency shutdown, when the emergency shutdown electromagnetic valve is in undercurrent orin overcurrent, the emergency shutdown electromagnetic valve is switched to the standby electromagnetic valve for emergency shutdown, when the emergency shutdown electromagnetic valve is in overcurrent, the loop of the emergency shutdown electromagnetic valve is cut off for protection, and during a non-emergency shutdown period, the situation that an overcurrent alarm lamp is turned on not only shows that the emergency shutdown electromagnetic valve loop is in overcurrent, but also shows a failure and a short circuit of the switch module which controls the emergency stop electromagnetic valveloop.