Vattenfall said the change in market conditions had lowered risk and created a more stable financial return in renewable energy projects.
Under the changes, approved at an extraordinary general meeting this week, adjusted net debt has been altered to 22-27%, from the 22-30% target set in 2012.
Vattenfall has also removed net debt-equity ratio, which was previously 50-90%.
The return on capital employed as also been reduced to 8%, from 9% before.
In a change to its dividend policy, meanwhile, Vattenfall said it should amount to 40-70% of post-tax profit, a change from 40-60%.
The company's CEO Magnus Hall, said: "The new targets are an adjustment reflecting the reality we live in.
"Looking at new assets in which we will invest in the future, mostly renewables, returns are lower than in the past.
"As such, the goals reflect our strategy of continuously delivering energy solutions that are better for the climate.
"The ambition is, of course, for returns to be higher than our owner's requirements," he added.
In late October, Vattenfall reported its underlying operating profit in Q3 amounted to a SEK 300m (€31m) loss.
Vattenfall said the loss was due to cable and grid outages for some of its offshore wind projects.
The state-owned firm, however, recorded a 56% increase in underlying operating profit in the first nine months of 2017.
Along with its third quarter results, Vattenfall has also announced a €200 million investment in the repowering and expansion of the Wieringermeer project in the Netherlands.