It is an effective technology of recycling organic fractions of municipal solid waste as light-weight aggregates (LWA) fired in trefoil rotary kiln. This paper studies the optimum batch formula and optimal calcination conditions of LWA made from municipal solid waste , clay and coal fly ash.The results indicate that: 1)optimum batch formula (dry mixture ration) is 15.38% of BMW，14.85% of clay，69.77% of coal fly ash; 2)optimal calcination conditions are preheating temperature of kiln:500 ℃, sintering temperature:1190 ℃, holding time of sintering temperature: 4 min. The performance testing indicators of aggregate fired under best experimental parameters shows: bulk density is 605 kg/m3, cylinder compressive strength is 3.0 MPa, 1hr water absorption is 11.0%, apparent density is 0.93, all of the targets meet 700 grade light aggregate of GB/17431.2—1998 standards; the results of leaching test are lower than hazardous constituents concentration limits of GB/T 5085.3—2007 standards, LWA is not hazardous to environment.