In order to determine the stability of bamboo leaf flavonoids (BLF) during different heat processing treatments, Acidosasa edulis (AE), Phyllostachys heterocycla (PH), Dendrocalamopsis oldhami (DO) and Pleioblastus amarus (PA) were used as experimental materials to study flavonoid variation during three common different food heating processes: microwave heating, baking and steaming. The results showed that different heating processes caused significant differences in blf content, especially in the process of steaming, which resulted in the loss ratio ranging from 34.25% to 71.27%. After baking, the loss ratio of AE reached 68.60%, and the loss ratio of other three bamboo species ranged from 15.80% to 33.06%. Thus, the best heating process is microwave heating with a loss ratio less than 30.0%. The stability of BLF during heating processes is closely related to the species and content of flavonoids. To analyze the primary cause of BIF loss, we used the HPLC-ESI-Q-TOF-MS/MS method to study BLF types and content of four bamboo species. Based on the results, we conclude that the flavonoid of O,C-Di-glycosylflavones could not tolerate microwave heating and baking; Mono-C-glycosylflavones has high heat tolerance, and shows good stability during baking and steaming; the flavonoid of O-glycosylflavones can tolerate microwave heating; while the stability of Di-C-glycosylflavone is not good under microwave heating.