A　measurement　method　of　liquid＇s　refractive　index　by　means　of　single-shot　dual-wavelength　off-axis　digital　holographic　microscopy　system　and　a　microfluidic　chip　is　presented.　The　refractive　index　of　liquid　filled　in　the　microchannel　of　a　microfluidic　chip　can　be　calculated　directly　with　the　unwrapped　phase　map　obtained　at　the　synthetized　wavelength,　without　requirement　of　knowing　another　liquid＇s　refractive　index　as　a　measurement　reference.　Moreover,　it　also　avoids　the　influence　of　the　accuracy　of　the　known　refractive　index　on　the　refractive　index　to　be　measured.　The　refractive　indices　of　salt　solutions　and　sucrose　solutions　in　the　several　concentrations　are　achieved　in　the　experiments,　which　verifies　that　the　measurement　of　liquid＇s　refractive　index　is　accurate　and　reliable.　With　the　merit　of　accurate　measurement　of　liquid＇s　refractive　index　based　on　the　one-frame　dualwavelength　hologram,　it　is　expected　that　this　approach　will　be　employed　to　detect　in　real-time　the　fluid＇s　parameters　related　to　its　refractive　index.