Copper wire bonding process is widely used in the electronic packaging of system integration with various heterogeneous and homogeneous components due to the advantage of cost. In this paper, an achievement of parallel microgap resistance welding with 40-μm copper wire on 300-nm Au-plated quartz pendulous reed used in precision mechanical and electrical product was presented. Research on orthogonal design of experiment was carried out, and the effect of process parameters was discussed on the shape of bonding interface, tensile force, and shear force by variance analysis. It is shown that too large a heat input and electrode pressure can cause the gold layer to wrinkle or fuse and cause bonding interface mechanics performance to fall sharply. A group of optimized process parameters (0.84 N of bonding pressure, 0.45V of bonding voltage, and 17 ms of bonding time) is obtained. Reliability tests including the thermal shock, random vibration, and electric aging tests on optimized process parameters were carried out, and the mechanical properties and physical properties of the bonding interface were mainly focused. It is shown that the bonding interface resistance increases slightly and the overall bonding interface tensile strength falls slightly after 500 cycles of thermal shock test. However, there is no change during the random vibration process. When electric aging time is less than 200 h, bonding interface morphology does not change and there is no crack. When electric aging time is 360 h, bonding interface deforms and crack occurs. When electric aging time reaches 720 h, bonding interface crack area increases, and it eventually fails. It is experimentally proved that a bonding interface with better performance can be achieved by parallel microgap resistance welding with 40-μm copper wire on 300-nm Au-plated quartz pendulous reed.