What is the innermind of Julia in '1984'?Julia seems a spy of Inner Party, but I think she may not be the member of inner party; she became a spy...

Julia is not a spy.  She repeatedly tells Winston in their
conversations in the apartment above the antique store that she doesn't care about
revolution or overthrowing the party.  She is not an Inner Party member, or she wouldn't
be able to associate with Winston.

She is intrigued with
sex, with living her life for her own pleasure (fully knowing that if she is caught, it
could mean death for her and for her current partner), and with being smart enough to
engage in these activities without the Party's knowledge.  She tells Winston that she
has had many partners, and some of them were with Inner Party members.  This is one of
the reasons, Winston states, that he loves Julia so
much. 

One wonders why Julia has been able to get along
with her activities secretly for so long.  It is my contention that had she not
connected with Winston, she would still be at her extra curricular activities.  Until
Winston, one can summise that Julia's partners were like she is...not looking to
overthrow the Party, but seeking sexual partners only for the pleasure, adventure,
and thrill it provides.  When she finds Winston (who openly hates the Party and
envisions its downfall), they both are captured and sent to the horrors of The Ministry
of Love and Room 101.