In order to get the characteristics and regulation of aircraft artificial rainfall work in emergency meteorological services, such as the forest fire fighting, background weather conditions of precipitation process and changes of in-cloud microphysical parameters after the feeding operation were analyzed by using data of cloud physics obtained from one artificial rainfall operation over the forest fire in Funing Region, Qinhuangdao, on April 17th, combined with data of weather, satellite and radar. The result showed that after the operation, the cloud body had a significant development with a increasing of cloud droplet water content. Cloud droplet concentration increased by approximately 30%-50% .Both the ice crystal concentration in the central part of cloud and precipitation particles in cloud showed an obvious increase. Precipitation in areas near the fire spot was 0.3-5.0 mm, which was vital for the firefighting. There were mainly 3 reasons which constrained the precipitation amount. Firstly, the weak westerly trough system was in north which narrowed the cloud band over the fire zone; Secondly, the cloud water content was low with a maximum value of 1.318 g/m3, so was the relative humidity in the early stage; Last but not the least, the stratocumulus which was under the altostratus was weak and there was a dry layer between these two, which could affect the formation and development of the precipitation particles.