Delegates at the party’s autumn conference in Glasgow overwhelmingly supported a motion calling for the immediate repeal of the Sovereign Grant Act 2011.
The legislation resulted in a major financial boost for the Royal Family by paying them a proportion of profits from the Crown Estate, which has around £272m of assets in Scotland.
The royal household has seen its income increase significantly since the Act was passed, receiving £76m this year compared to £31m in 2012/13.
The motion called for profits from the Crown Estate, which includes 370,000 hectares of rural estates including Glenlivet Fochabers in Moray, to be “spent on the wider public good” instead.
Julie Hepburn, the SNP’s political education convenor, insisted that the motion was not about people’s “views on the monarchy” but about the best use of public money.
She described the Sovereign Grant as the “epitome of privilege” and a “symbol of everything that is rotten at the core of the UK political system”.
Under the current arrangement, the royal household’s percentage of profits from the Crown Estate cannot fall compared to the previous year, with payments rounded up to the nearest £100,000.
Ms Hepburn said this was “the equivalent of the Royal Family winning the national lottery every single year”, claiming that “Her Majesty is purring all the way to the bank”.
She added: “This is our money – money that could otherwise be spent on the public good.
“At a time when the UK Government is insisting we all tighten our belts, particularly the most vulnerable, because there is no money, there can be no moral justification for giving just one family over £70m.”
SNP MP Alison Thewliss said the Crown Estate made significant profits from offshore wind farms, amounting to £328m to date, money she said could have been invested in communities instead.
Brian Nugent of the SNP’s Shetland branch told the conference that while he was “all for knocking the Royal Family”, the motion should be changed to insist that any income recovered from the Crown Estate was spent on local areas.
Another speaker, Graeme McCormick, said the motion was “futile” and “mealy-mouthed”, calling for the party to hold a proper debate on whether it supported the monarchy at all.
“Let’s be proud that we want an independent Scotland so that we can decide...what our constitution’s going to be and who should be our head of state,” he added.
Although the Sovereign Grant Act is a matter for Westminster, the Scottish Government is being handed more powers over the Crown Estate and has launched a consultation on the issue.
The SNP’s current policy, which was unchanged by the motion, is for a proportion of revenue generated by the Crown Estate in Scotland to be given back to local communities.