An important vein-type copper metallogenic belt developed in western Yunnan, SW China. Previous researches mainly linked the Cu mineralization to the evolution of Lanping Basin, ignoring the shearing process of the Chongshan shear zone, however. Maocaoping vein-type Cu deposit, discovered recently, is located in the south of the the copper metallogenic belt, belonging to Chongshan shear zone. Geological features were determined during detailed field work, and the structural characteristic of the veins was confirmed by microscopic observation, as well. This paper gives the hydrothermal muscovite Ar-Ar age of the metallogenic period, and discuss the relationship between Cu mineralization and regional shear deformation in Maocaoping vein-type Cu deposit based on these work. Hydrothermal minerals in Maocaoping are presented as alteration halos, ore-bearing veins parallel to shear foliation of host rocks (named as A1 vein), and ore-bearing vein crosscutting shear foliation (named as A2 vein). Minerals of the alteration halos, A1 veins, and A2 veins have the characters of transitional growth, and crosscut each other in part. This phenomenon indicates that the minerals in them were generally formed in the same mineralization event, but precipitated during different stages. The alteration halos are mainly composed of tourmaline and quartz formed in earlier stage. The minerals are well orientated, parallel to shear foliation of host rocks in the halos, implying vein formation under stronger shear stress. Subsequently, A1 veins were formed, which mainly composed of tourmaline, quartz, calcite, dolomite, muscovite and chalcopyrite. The minerals are weaker orientated, approximately parallel to or oblique to shear foliation in the veins, suggesting the vein formation during waning stage of shear stress. A2 veins were finally formed and had similar minerals to the A1 veins. The minerals were non-orientated or grew with comb texture in the veins as the result of extensional filling, suggesting that the veins were formed immediately after shearing and possibly generated by nearly horizontal compressive stress. In summary, the mineralization is a result of the final stage of the shearing action which experienced a waning process.40Ar/39Ar dating of muscovite from the A1 veins determines a plateau age of 20.34±0.19 Ma, representing the mineralization age of the Maocaoping Cu deposit. This age also suggests that the shear deformation in the Maocaoping area ceased at about 20 Ma, apparently prior to the cessation timing (~14 Ma) in other areas in Chongshan shear zone. In conclusion, the Maocaoping vein-type Cu deposit was formed during the shearing of the Chongshan shear zone (late stage), and mineralization was controlled by tectonics related to the final-stage shearing deformation, which means that it is related to the evolution of the Chongshan shear zone. This study suggests that the origin of the vein-type Cu deposit in the west of Lanping Basin has a close relationship with the evolution of the Chongshan shear zone.