Abstract: A set of experiments is designed and conducted in 2m3 cloud chamber to study the possible effects of explosion on cloud droplets coalescence. A simulating explosion is used to generate shock wave and precipitation method and FSSP probe of PMS are used to monitor the droplet spectra. The data show that the droplet spectra become broader and the larger droplet concentrations increase in 2 minutes after explosive shock wave influence (acoustic pressure is about 130dB). It seems that explosion in cloud could promote the droplet coalescence process and produce some larger droplets which would grow through further coalescence. The result could provide an explanation of explosion effects on warm cloud modification.