The party's justice spokeswoman Margaret Mitchell told the Scottish Parliament it would be a good way for outgoing officers to use their experience, while freeing up younger officers for frontline duties.
There are currently more than 50 campus officers operating in Scotland, working to improve relationships between the police and communities.
An evaluation of Scotland's campus police officers in 2010 found their presence "helps improve relations between young people and the police and make school environments feel secure".
Ms Mitchell said: "It would allow retiring police officers to continue to use their experience for the public good, while allowing them a way to wind down from full police duties. That would enable other officers who are based in schools to get back onto the frontline."
Ms Mitchell said Justice Secretary Kenny MacAskill had already given a positive response to her suggestion.
She added: "While we don't know if the number of school campus police has increased or decreased under Police Scotland, it's gratifying to know Mr MacAskill will look into this further."