North China's Tianjin Municipality will forbid outdoor burning of straw to reduce air pollution.
One of China's big cities, Tianjin is next to Beijing.
From March 1, open air burning of straw can be fined at a maximum of 2,000 yuan (291 US dollars), Xinhua news agency reported.
Although many local governments forbid straw burning, farmers continue to do so as there is no profit in recycling it and leaving it on farmland affects the next season's crop growth.
The regulation passed on Friday encourages farmers to use straw shredders during harvesting so as to return the material as bio-fertilizer.
No farming subsidy will be granted if the practice is not enforced, said the regulation passed by the city's legislature.
Environmental monitoring data shows the number of days of heavy air pollution in Tianjin increased in 2016.
The city issued a red alert for pollution in mid-December when schools and traffic were disrupted by heavy smog.