Steam cooker and backflow prevention device thereof

A backflow prevention device comprises an upper chassis, a lower chassis, a seal member, and a resilient member, wherein the upper chassis defines a receiving space passing through a bottom of the upper chassis,

• the lower chassis defines an air flow channel,
• a part of the lower chassis is accommodated in the receiving space of the upper chassis, and fixedly connected to an inner wall of the upper chassis,
• the upper chassis and the lower chassis are mounted to a pot, and the seal member is received in the receiving space,
• the resilient member is resiliently mounted between the seal member and the upper chassis, and a resilient power of the resilient member pushes the seal member to resist against and seal the air flow channel,
• wherein the backflow prevention device further comprises a nozzle fixed to a main body and configured to be inserted into the air flow channel to push the seal member to move upwards, and the nozzle defines a cross groove.