A phase current integration method for diagnosing a fault in a switched reluctance motor power converter determines whether the main switch of a switched reluctance motor power converter is experiencing a short circuit or an open circuit fault by measuring a phase current io(t) transient value of said converter in a non-fault state as well as a present phase current i(t) transient value of said converter, so as to obtain, by an integration operation, an integration value SnO of a phase current during a certain period under the non-fault state, and an integration value Sn of a phase current during a certain period under a present state, the ratio En of the two values indicating a fault characteristic value.