On April 2015, with an aim to assess the risk to human beings and the environment during the process of transportation, treatment and collection demonstrations, the team of Project CFL in Beijing carry out pre-lab experiment for testing the mercury emission when lamp breaks. During the test, the team conducted comparative experiments between single WFL and 10 pieces of WFL. They tested the density of mercury emission, in order to examine the influence the period of window leakage on the density of mercury. The lab experiment was conducted in a 2*2 square meters closed space, imitating the natural wind condition. Based on these, they found out that when single WFL breaks, the surrounding density of mercury showed a decrease trend, while there is no evident difference between the figure monitored in 15 min and 30 min. Therefore, this pre-lab experiment testified that the mercury emission will be diffused in 15 min in wind flow condition.