The estrus spawning of the forest frog includes three stages: out of the river, holding pairs, and spawning.

Adult forest frogs cannot spawn in the rivers where they overwinter, and must be transferred to still water areas to spawn, a process known as the out-of-river stage. The water depth of the spawning pool of the forest frog is usually 10 to 15 centimeters, and the deepest is not more than 25 centimeters.

Generally, most of the forest frogs start to hold pairs about 5 hours after they come out of the river, and they start to lay eggs about 6 hours after they hold pairs. In case of sudden cooling, snowfall and other unsuitable conditions for spawning, the frogs that are coming out of the river will stop coming out of the river immediately, and the frogs that are coming out of the river will stop holding pairs to spawn, and will hold pairs to spawn only when the natural conditions are suitable.

The frogs start to drop eggs 7 to 10 days before spawning. Egg drop is the maturation of the egg cell, from the ovary into the body cavity, and through the fallopian tube into the uterus. Egg dropping takes place in the water and is completed when the frog comes out of the river.

The water temperature suitable for mating between male and female forest frogs is 8 to 10 degrees Celsius. Forest frogs do not have external genitalia, breeding male frogs climb to the back of the female frogs, with the forelimbs tightly hold the female frogs forelimbs under the armpits, through the hold on the mutual stimulation, contributing to the female frogs ovulation, male frogs spermatozoa, spermatozoa in vitro to complete the fertilization process.