The liquid crystal bubble defect occurred in large-size products under high-temperature-operation-test are systematically analyzed and summarized from the occurrence of the defect, hypotheses on the mechanism, and through experimental tests to verify the hypothesis mechanism. It is concluded that the adhesive of the sealant is reduced greatly in the high temperature environment, resulting in the formation of liquid crystal bubble defect. At the same time, it is demonstrated that by selecting sealant materials with high Tg point and optimizing the bonding interface, the high-temperature adhesion is improved, thereby the problem is solved effectively, the product quality is ensured, and the production yield of LCD monitors and customer satisfaction are improved.