The invention discloses a method for producing gas by coke gasification. According to the method, oily dust crude gas enters a cyclone separator to be separated to obtain crude gas of which the oily dust content is 1 to 80 mg per cubic meter and oily dust; the oily dust is enriched to the bottom of the cyclone separator, an ash tank is pressurized by using the gas or an inert gas until the pressure of the ash tank is consistent with that of the cyclone separator, and an oily dust discharge valve is opened for discharging the oily dust to the ash tank; the obtained crude gas enters an integrated waste heat recovery device, heat is recovered in grades through a superheater, a heat recovery device II and a heat recovery device I, and the recovered heat generates three-grade steam of low-pressure saturated steam, medium-pressure saturated steam and superheated steam. The method and equipment for producing the gas by the coke gasification disclosed by the invention have the advantages of no gas scouring water and capabilities of carrying out grading recovery and reutilization on gas waste heat energy and further producing the steam of different grades.