A liquid crystal display panel and a manufacturing method thereof, and a frameless liquid crystal display device are provided. The liquid crystal display panel includes an array substrate, a counter substrate, and a liquid crystal layer. The array substrate includes a first region and a second region. The counter substrate includes a third region and a fourth region. A black matrix covers one side of the fourth region, and a metal light-shielding portion is disposed on one side of the array substrate facing toward the counter substrate. The metal light-shielding portion covers the second region and a part of the first region adjacent to the second region, and a side-edge of the metal light-shielding portion near the first region is located below the black matrix. Through adding the metal light-shielding portion, light leakage occurring on edges of a frameless liquid crystal display device is solved, and display quality is improved.