This paper presents the fabrication of all plastic microfluidic devices with built-in 3-D fine microstructures. The built-in micromeshes in the microchannel were formed by the combination of the multi-angle inclined backside exposure and top side exposure of thick Epon SU-8 photoresist on a glass substrate. The lift off method, using LOR (Lift-off Resist) as a sacrificial layer, was utilized to remove the all SU-8 device from the substrate. The monolithic plastic structures realize uniform physical and chemical properties required in microfluidic devices for practical applications. Fragmentation of a water droplet in organic carrier formed by two phase flow was demonstrated.