Improving mechanical properties of wound dressings and achieving personalized automatic real-time in situ deposition are important to accelerate wound management and repair. In this study, we reported a home designed automatic in situ deposition device based on solution blow spinning (SBS) to prepare PLGA/PLLA composite nanofibrous membranes for wound dressing. Polymer solution and in situ deposition conditions including air pressure, spinning distance, solvent extrusion rate, and spinning rate were optimized by orthogonal experiments and characterized with dynamic mechanical analysis. Microscopic morphology and physical properties of the prepared PLGA/PLLA composite nanofibrous membranes show that the strength, adhesion, water vapor transmission rate, water retention, water absorption, degradation etc., were sufficient for wound dressing applications. To investigate the possibility as a biomedical wound-dressing material, tannic acid (TA) was incorporated with PLGA/PLLA composite nanofibrous membranes. The resultant PLGA/PLLA/TA composite nanofibrous membranes exhibited good biocompatible and exceptional antibacterial properties against both Escherichia coli and Staphylococcus aureus. A pilot animal study illustrated the potential of this in situ deposition of PLGA/PLLA/TA composite nanofibrous membranes across multiple applications in wound healing/ repair by reducing the formation of wound scar tissue and overactivation of fibroblasts.