Probabilistic transfer matrix (PTM) is a more accurate approach to estimate the effects of soft errors on gate level circuit reliability.However

the existed method can only be used for small-scale circuits so far.This paper presents a serial method of circuit reliability calculation based on PTM.The circuit under evaluation is partitioned into proper scale modules that their reliability can be calculated by the original PTM.Then the reliability of the whole circuit is calculated based on the serial reliability model and reliability values of all modules.The proper circuit partition parameter (i.e.partition width) is gotten by experiments with 74-Series circuits.The proposed new reliability calculation method is applied on ISCAS85 benchmark circuits.It shows that our method can be used for larger non-redundant combinational circuits.It is verified that the new method is consistent with the reliability calculation method recommended by MIL-HDBK-217 standard by using some ISCAS85 circuits.