In order to satisfy the demand of NETD test for thermal imaging systems,four time components and three space components of noise of thermal imaging systems are discussed based on the 3D noise model, and the conventional noise computation method is analyzed.On which basis,a simple algorithm based on standard deviation is put forward,which can reduce the amount of computation and enhance test efficiency.The engineering test system is designed,and the calculation method and test process of NETD index are presented.Through experiment,two test algorithms for 3D noise are verified and analyzed.A comparison test with the imported equipment is conducted,and it is proved that the NETD test result of the proposed system is accurate and repeatable.It has been applied to the performance test of several kinds of thermal imaging equipment,which meets the requirement of engineering support.