The invention discloses a method for manufacturing cement bricks from green mud and boiler ash recycled by utilization of pulping alkali. The method is as follows: firstly, the following raw materials are weighed, by weight, 25-30% of green mud, 18-38% of boiler ash, 35-55% of limestone powder and 1-1.5% of cement, the above raw materials are mixed uniformly, and a mixture is obtained; secondly, the mixture is subjected to molding at a pressure of 40-50 MPa, and green bricks are obtained; thirdly, the green bricks are subjected to curing and cement bricks are obtained. The employed green mud does not need dewatering or alkalinity reduction, energy consumption is saved greatly, the brick manufacturing cost is lowered, the green mud doping amount is high, the cement doping amount is lowered than a conventional level, the waste utilization rate is raised greatly, the cement expense is saved, and the brick manufacturing cost is lowered further.