Droplet-based microfluidic devices have shown great potential in biomedical applications. When proteomics bioanalysis or biomarker identification is required, off-line microfluidic chip interfacing with mass spectrometry (MS) is necessary. This reported work has focused on the use of numerical simulation of microdroplet formation and dripping for a droplet-based microfluidic-chip interfacing with off-line laser desorption/ionisation MS target substrate. Unlike most studies on the microdroplet formation at the liquid-liquid phase, this work has investigated the microdroplet formation at the liquid-gas phase at various injection flow rates and inner microchannel surface wettability to meet microfluidic-chip-MS interfacing requirements. After the microdroplet formation, subsequent microdroplet dripping analysis was performed. The effects of inner microchannel and outer orifice surface wettability are discussed.