Notoplana humilis actively spawns in spring and early summer. Embryo undergoes spiral cleavage, epibolic gastrulation and uses macromeres to deposit yolk. The larva which needs about 20 days to hatch at 14-16℃, however, is not a Müller's type. The larva is planktonic for 1 week, demersal for 2 weeks, and undergoes gradual metamorphosis to become a juvenile flatworm.