By calculating the first order variation of the dual mixed volumes, we put forward a new concept Orlicz multiple dual mixed volumes. The classical dual mixed volumes and dual Aleksandrov-Fenchel inequality are generalized to the Orlicz space... We establish dual Orlicz Aleksandrov-Fenchel inequality and a new concept of Lp multiple dual mixed volume and Lp dual Aleksandrov Fenchel inequality are first derived here, too. The dual Aleksandrov-Fenchel inequality and the Lp-dual Aleksandrov-Fenchel inequality are all special cases of the dual Orlicz-Aleksandrov-Fenchel inequality. As an application, a new dual Orlicz-Brunn-Minkowski inequality for the Orlicz harmonic addition is also established. (read more)