The classic method of moment is extended to account the slips of velocity and temperature between the liquid phase and the gas phase in condensing flows. The moments of droplet size distribution are defined on the liquid phase, instead of on the mixture of liquid and gas, so that the gas phase and the liquid phase can be treated separately. The interphase interaction is realized through source terms which include the mass, momentum and energy exchanges. As a demonstration, this new method of moments is integrated into a numerical method and is applied to a vortex shedding problem with condensation. Due to the very strong velocity slip, a dry zone is found in the vortex core region. This phenomenon was experimentally observed but not discovered by the classic moment method. (C) 2017 Elsevier Ltd. All rights reserved.