The invention provides a checking method of 'three noes' devices. The method is applicable for rapid processing of a computer. Risk management and control ability for the 'three noes' devices is strengthened and operation risks of the devices are pre-controlled. The checking method comprises following steps of firstly finding out switching value VS1 satisfying a searching condition S from a switching value record V0 in time interval [T1, T2], taking out a switching value record VSS1 which is proximate to the time T2 and marking searching conditions in which switching value records cannot be found in S as S1; then finding out a switching value VS2 satisfying a searching condition from a switching value record in time interval [T1-deltaT, T1], taking out a switching value record VSS2 which is proximate to the time T1 and marking searching conditions in which switching value records cannot be found in S1 as S2 until searching conditions in which satisfied conditions cannot be found are zero; and finally subtracting the time record of the selected switching value recode from the current time, selecting devices whose difference values exceed the threshold value delta T and carrying out examination operation on the devices.