According to the data and communication security standard IEC 62351 in power systems， a password authentication method for data and communication security in substations is investigated， which can not only satisfy the authentication demand for substation communication security， but also ensure minimum calculation workload and transport expenses. By comparing a few international top password techniques and analyzing the access security model for the IED in IEC 61850， this paper presents the security remote password（SRP） protocol to utilize the authentication when the application association of IEDs is set up in substation automation. Finally， the authentication between IEDs is taken as an example， the improved SRP is introduced and the concrete authentication process between IEDs is designed. The research results are of significance as a reference to implementing IEC 62351 standards in substation automation.