The invention discloses a method for utilizing incineration fly ash as a calcium-increasing passivation agent of town sludge and aims at solving the problems of low contents of organic matters, higher content of heavy metals, unstable property, high water content and difficulty in transporting in the town sludge. The invention provides an economic and low-pollution mixed treatment method for the town sludge and the incineration fly ash for solving the problems according to the characteristics that the incineration fly ash has high calcium content and strong hydroscopicity. According to the method, components and the water content of the town sludge are required to be determined and then the town sludge is mixed with the incineration fly ash; the pH value of a mixture is enabled to be 9-11; the mixture is kept still at the room temperature for 2-7 days and then is filled in the ground; and the calcium content in the incineration fly ash can be used for improving the pH value of the sludge, passivating the heavy metals and sterilizing. The incineration fly ash is used as a drying agent of the sludge; the water content of the stabilized mixture of the sludge and the incineration fly ash is 20-40 percent; the transportation and subsequent landfill are facilitated; and the treatment cost of the sludge is reduced.