The invention provides an air inlet structure of a plastic wine barrel, belongs to the technical field of wine equipment, and solves the technical problem that stability of wine discharging is greatly affected by an existing wine spear. According to the air inlet structure of the plastic wine barrel, the plastic wine barrel comprises a barrel body, a barrel opening of the barrel body is fixedly connected with a wine spear head and a guide sleeve, and the guide sleeve is positioned in the wine spear head. The air inlet structure of the plastic wine barrel is characterized in that a joint is arranged in the guide sleeve and can move vertically, a plurality of guide projections which can guide the joint to move are arranged between the inner wall of the guide sleeve and the outer wall of the joint, an air inlet channel is formed between each two adjacent guide projections, the upper ends of the air inlet channels communicate with a center hole of the wine spear head, the lower ends of the air inlet channels can communicate with a cavity of the barrel body, and a sealing piece which can seal space between the guide sleeve and the joint is arranged between the guide sleeve and the joint. The air inlet structure of the plastic wine barrel has the advantages of relatively high stability and good wine discharging effect.