The invention discloses a condenser and an air conditioner, relates to the technical field of air conditioners and is invented in order to improve the heat exchange effect of the condenser in the prior art. The condenser comprises multiple heat exchange pipelines which sequentially communicate with one another; each heat exchange pipeline is provided with a refrigerant inlet and a refrigerant outlet; multiple heat exchange pipelines include first heat exchange pipelines and second heat exchange pipelines; the first heat exchange pipelines are arranged, close to the refrigerant inlets respectively; the second heat exchange pipelines are arranged, close to the refrigerant outlets respectively; and the diameter of each second heat exchange pipeline is larger than the diameter of each first heat exchange pipeline. The condenser provided by the invention is used for performing heat exchange with a heat transfer medium.