Pectin methylesterase (PME) exists naturally in plant tissues and can catalyze the demethyl esterification of high-ester pectin into low-ester pectin, which affects the hardness, juice yield and other texture and processing quality of fruits and vegetables. During the processing of fruits and vegetables, PME needs to be inhibited in order to avoid undesirable quality attributes such as excessive turbidity in fruit and vegetable juices, softening of canned fruits and vegetables, and separation between fruit skin and flesh in seasoning sauce such as chili sauce. One the other hand, in order to improve the juice yield of fruits and vegetables and produce low-ester pectin, exogenous PME needs to be added into products. Currently, there are few studies on activating endogenous PME to improve food processing. Therefore, this article focuses on the factors that promote the catalysis of plant endogenous PME on pectin demethylesterification, the underlying mechanism and its applications in fruit and vegetable storage and processing, which hopefully will provide a reference for the application of plant endogenous PME in fruit and vegetable processing.