The Forming limit diagram is an important tool in metal forming processes, as it indicates the failure limits for ductile damage and onsite necking. Forming of micro-thin metal sheets (thickness less than 100 microns) is more difficult and requires more precision. This type of miniaturisation in forming process with the components produced with dimensions up to few millimetres is defined as a micro-forming. There are many differences in the properties of materials and physics of process when macro process is converted to micro. In this work, an experimental test of thin alpha brass sheets of 40 µm and 90 µm with different orientations to rolling directions (0\textordmasculine, 45\textordmasculine, 90\textordmasculine) was performed to determine the forming limit curves. Hemispherical punching test designed for micro forming is performed according to ASTM-2218-14 standard test using sample of Uni-Axial, Intermediate Uni-Axial, Bi-Axial, Intermediate Bi-Axial and Plane Strain paths to obtain limit strains. Explicit dynamic numerical analysis with Abaqus platform is used to model micro-forming process and forming limit curves are plotted. Numerical results have been validated with experimental results.