Mrs Parkin, who resigned as a Green national spokesperson last month claiming in-fighting was damaging the party's cause, is due to address the conference in Wolverhampton today.
Her resignation was followed by the decision of Jonathon Porrit, the former Friends of the Earth campaigner, to stop taking an active role in the party, saying he was disillusioned.
Mrs Parkin is due to speak on the subject of world debt, but today 'No Parkin' stickers appeared in the conference hall.
Radical Greens, angry that she described the party as a 'liability', want her to sever all links.
The Greens failed to make an impact in the general election. All candidates lost their deposits in 254 seats contested, receiving on average 1.3 per cent of the vote.