The work aims to obtain high-precision glass molding die by processing C71500 micro-pyramid array of copper-nickel alloy with Low Speed Wire Cut Electrical Discharge Machining (LS-WEDM) technology. Single-factor process experiments were carried out to study the effects of pulse width, pulse interval and wire speed on surface quality and dimensional accuracy. Super-depth 3D microscope, laser-scanning confocal microscope and scanning electron microscope were used to measure and analyze the surface roughness and arc radius of the micro-pyramid array die after cutting. Besides, the heterogeneity of cusp radius of the micro-pyramid array die was studied, and the optimal process parameters were obtained by comprehensive optimization. The surface roughness of the processed cusp decreased with the decline of the pulse width, firstly decreased and then increased with the increment of the pulse interval, and decreased with the increment of the wire speed. The arc radius of the cusp decreased with the decline of the pulse width, and decreased with the increment of the pulse interval and the wire speed. After comprehensive optimization, micro-pyramid array die cusp could get the optimal surface roughness (Ra=9 nm) and the minimum cusp radius (5.41 μm) when the pulse width was 6 μs, the pulse interval was 14 μs and the wire speed was 6 m/s. Compared with the experimental results before optimization, the surface roughness was reduced by 60.9%, and the cusp radius was reduced by 53.0%. The change of contact area between electrode wire and workpiece electrode was the main reason for the heterogeneity of cusp radius of micro-pyramid array after LS-WEDM. A micro-pyramid array die with uniform cusp radius, micron-scale dimensional accuracy and nano-scale surface roughness can be fabricated on the copper-nickel alloy material by LS-WEDM. This research work is instructive and meaningful to micro-pyramid array die of copper-nickel alloy by LS-WEDM.