This paper investigates the pore structure characteristics of alkali-activated fly ash mortar affected by different factors via a mercury intrusion test，and explores the mechanical properties of specimens from the view of pore structure characteristics． Test results indicate that ( 1) with the growth of curing age，the porosity of alkaliactivated fly ash mortar specimens increases，the average pore diameter decreases，and the distribution of internal pores changes from a discrete macroporous structure to a more uniform form; ( 2) both the curing temperature and the mass ratio of the excitant have an impact on the strength of specimens and the distribution of pore diameter， concretely，higher curing temperature may result in more fully hydration of fly ash，and the internal aperture of the structure may decrease with the growth of curing age，thus resulting in a higher compressive strength of the specimens; and ( 3) in the several above-mentioned factors，mass ratio has the most complex effect on pore structure， concretely，a continuous variation of mass ratio may result in a periodic change of pore structure distribution and compressive strength．