The invention discloses an aquatic offspring seed cultivating and breeding device which comprises a reservoir and a breeding jar, wherein a heater, an oxygenation device and a water through pipe are arranged in the breeding jar; the heater and the oxygenation device are arranged in the breeding jar and are respectively connected with a power supply; the bottom of the breeding jar is high in periphery and low in middle and is inclined to the center of the bottom of the jar with the horizontal plane in an angle of 10-20 degrees; the water through pipe comprises a water through pipe I and a water through pipe II; the water through pipe II is arranged in the water through pipe I and is respectively connected with a blow-off pipe and a drainage pipe; an automatic timing blow-down valve is arranged on the blow-off pipe; the reservoir and the breeding jar are connected through a water inlet pipe; an automatic timing water inlet valve is arranged on the water inlet pipe. The aquatic offspring seed cultivating and breeding device can realize full-automatic water change and pollution discharge, is good in water treatment effect, simple in operation and convenient to use, is widely applied to cultivating and breeding offspring seeds of various aquaculture species, can serve as a design model for transforming a large-scale aquaculture pond and also can serve as miniature test equipment for cultivating and breeding offspring seeds of various aquaculture species.