Abstract: An easily assembled filter adaptor assembly has a front mounting ring, a holding ring, a rear mounting ring, multiple intermediate rings, and at least one inner mounting ring, which are detachably connected with each other. Filters are selectively held between the front mounting ring, the holding ring, the intermediate rings, and the at least one inner mounting ring. The filter adaptor assembly has a simplified and compact structure. Accordingly, volume of the filter adaptor assembly can be reduced. Furthermore, numbers of the intermediate ring and the inner mounting ring can be increased or decreased so as to adjust numbers of the filters that can be assembled in the filter adaptor assembly.