The aim of this study was to explore the expression of PI3K, AKT, and P-AKT, and to investigate the role of PI3K/AKT signaling pathway in thin endometrium. We included 40 women treated in affiliated Shenzhen Nanshan People's Hospital of Guangdong Medical University for endometrial conditions between August 2013 and January 2015, 20 with a normal endometrium, and 20 with thin endometrium. The expression of PI3K, AKT, and P-AKT was evaluated by the immunohistochemical S-P method. The expression of PI3K, AKT, and P-AKT proteins was significantly lower in the thin endometrium group than in the normal endometrium group (P < 0.05). The expression of PI3K and AKT was positively correlated with the expression of P-AKT. The expression of PI3K, AKT, and P-AKT proteins in the thin endometrium decreases during the proliferative phase, and this process could be associated with PI3K/AKT signaling.