Abstract: An epitaxial structure and a manufacturing method thereof, and a light-emitting diode (LED) device are provided. The epitaxial structure includes an N-type semiconductor layer, a multiple quantum well (MQW) active layer, and a P-type semiconductor layer sequentially stacked in a growth direction. The MQW active layer includes a front MQW active layer and a back MQW active layer sequentially stacked in the growth direction. The front MQW active layer includes at least two groups of first quantum barrier layers and first quantum well layers alternately stacked. The back MQW active layer includes at least two groups of second quantum barrier layers and second quantum well layers alternately stacked. A content of an aluminum (Al) component in each second quantum well layer is gradually increased in the growth direction, and a content of a gallium (Ga) component in each second quantum well layer is gradually decreased in the growth direction.