The invention provides a three-stage electro-hydraulic servo valve emergency protection device which comprises a two-position and three-way reversing valve, a thrust piston, a mandril and a powerful spring; wherein, the two-position and three-way reversing valve is arranged on a valve block used for installing a three-stage electro hydraulic servo valve; the thrust piston, the mandril and the powerful spring are arranged on a left end cover of the three-stage electro hydraulic servo valve. The device can be used in system failure protection and effectively improve the system security. The device has the advantages of simple structure, convenient achievement, reliable performance and timely protection, and is applicable to large-scale equipment employing the three-stage electro hydraulic servo valve, such as multiple degrees of freedom motion simulator, vibration test stand, etc.