Under a Jeremy Corbyn-led Labour government, shadow chancellor John McDonnell would scrap favourable tax regimes for industry in order to raise tax revenue.
But the UK Chamber of Shipping argue the plans would have the adverse effect and leave around 80,000 workers unemployed.
The shipping industry currently benefits from the "Tonnage Tax", introduced by John Prescott in 2000, which taxes companies based on the tonnage of their ships.
Chief executive of the Chamber of Shipping Guy Platten said:
Under Mr Corbyn's current plans there would be a £1.2bn black hole in the Exchequer's tax revenues and up to 80,000 workers left unemployed and reliant on state support. Labour's Tonnage Tax regime revived the industry and helped maintain the UK's position as a world leader in maritime services. This could now be at risk.
The Chamber of Shipping argues that the Tonnage Tax is replicated in most other maritime nations around the world and is "widely credited for reviving the UK's failing shipping industry".
Patten argued: "The shipping industry is a good corporate citizen, employing hundreds of thousands of people, paying its way, growing the economy and being ambitious to do more.
"But we are a global industry, and companies can relocate to other maritime economies at a moment's notice. If the Tonnage Tax was lost that's exactly what would happen.
"I know Mr Corbyn and the shadow chancellor, and their supporters, have strong views on the private sector. But I urge him to meet as many businesses large and small as possible - including in the shipping industry."