在扫描电镜上利用ＨＸ－ＴＳ２型拉伸台，对ＬＣ４高强铝合金常规热处理状态Ｔ６（时效至峰值强度）及退火状态拉伸时微裂纹的萌生及连接进行了原位动态观察。结果表明：在Ｔ６状态下，局部应力集中和应变引起的分散相（Ｐ）与基体（Ｍ）界面的分离及其本身开裂是微裂纹萌生的主要机制。退火样品除Ｐ／Ｍ界面分离和大块脆性相解理外还出现大量弯曲和扭折的滑移带。两种样品微裂纹的连接方式也不尽相同 The scanning electron microscopy (HX-TS2) was used to observe the initiation and connection of microcracks during the conventional heat treatment T6 (aging to peak strength) and annealing in LC4 high strength aluminum alloy. The results show that under the condition of T6, the separation of the dispersed phase (P) and the interface of the matrix (M) due to local stress concentration and strain and the cracking of the interface are the main mechanisms of micro-crack initiation. In addition to the P / M interface separation and bulk brittle phase facies, the annealed samples also showed a large number of bending and kinking slip bands. The connection between the two samples is also different