Transient electronic is an emerging field that designed electronic devices can be fleetly and partially (or completely) degraded when transiency is triggered. Here, a class of PVA-based degradable composite film was synthesized, whose physical properties allow it to be used as substrate material for transient electronic devices. We found the dielectric properties and dissolution rate of the composite film can be tuned by controlling the TiO2 nanoparticle addition. Based on the as-synthesized PVA/TiO2 composite film, patch antennas were further designed and fabricated. The antennas were found to possess excellent radiation performances at a frequency of 2.5 GHz. Most importantly, the antennas could be physically degraded within 1 h when immersed in pure water. This study shows that the PVA-based film is a good candidate substrate or supporting material for transient electronics. In addition, the design and manufacture methods reported here provide a reference for other transient devices with complex structure and function.