Abstract: In this experiment, lily bulbs of varieties Navona, Prato (Lilium spp.) were treated at different low temperature in different time to study the effects on the dormancy of the lily bulbs and the chilling requirement for breaking of the bulb dormancy. It found that 5℃ is the best effective temperature for dormancy broken. It’s no effect, if temperature is above15℃. There is only Navona lily bulb has the effect after -2℃ treatment. About 0℃ and 10℃, there are different results between the two lily cultivars. Navona ,the effect of dormancy broken at 0℃ is higher than it is at 10℃, Prato, the result is just opposite; The chilling requirement of the two lily bulbs are Navon,1200C.U; Prato, 840C.U.