The present invention discloses polymer surfaces with T-shaped microstructure and their fabrication method and applications. The polymer surfaces with the T-shaped microstructure are characterized in that T-shaped microposts arrange orderly on them, and nanobulges arrange orderly on the top surfaces of the micronails of the T-shaped microposts. A flexible insert is designed and manufactured according to the geometry of the T-shaped microposts, and nanogrooves are manufactured on the cavity surface of an injection mold according to the geometry of the nanobulges on the top surfaces of the micronails. The flexible insert is mounted on the injection mold cavity. An injection molding machine is used to inject the molten polymer into the injection mold cavity. Then the polymer surfaces with the T-shaped microposts, on the top surfaces of the micronails of which the nanobulges arrange orderly, are molded. The polymer surfaces with the T-shaped microstructure exhibit robust Cassie-Baxter state and moderate surface adhesion to water droplets, and can be used for quantitative collection, lossless transportation or micromixing of microdroplets.