Pressure　is　one　basic　parameter　involved　in　microfluidic　systems.　In　this　study,　we　developed　an　easy　capillary-based　method　for　measuring　fluid　pressure　at　one　or　multiple　locations　in　a　microchannel.　The　principal　component　is　a　commonly　used　capillary　(inner　diameter　of　400　mu　m　and　95　mm　in　length),　with　one　end　sealed　and　calibrated　scales　on　it.　By　reading　the　height　(h)　of　an　air-liquid　interface,　the　pressure　can　be　measured　directly　from　a　table,　which　is　calculated　using　the　ideal　gas　law.　Many　factors　that　affect　the　relationship　between　the　trapped　air　volume　and　applied　pressure　(p(applied))　have　been　investigated　in　detail,　including　the　surface　tension,　liquid　gravity,　air　solubility　in　water,　temperature　variation,　and　capillary　diameters.　Based　on　the　evaluation　of　the　experimental　and　simulation　results　of　the　pressure,　combined　with　theoretical　analysis,　a　resolution　of　about　1　kPa　within　a　full-scale　range　of　101.6-178　kPa　was　obtained.　A　pressure　drop　(Delta　p)　as　low　as　0.25　kPa　was　obtained　in　an　operating　range　from　0.5　kPa　to　12　kPa.　Compared　with　other　novel,　microstructure-based　methods,　this　method　does　not　require　microfabrication　and　additional　equipment.　Finally,　we　use　this　method　to　reasonably　analyze　the　nonlinearity　of　the　flow-pressure　drop　relationship　caused　by　channel　deformation.　In　the　future,　this　one-end-sealed　capillary　could　be　used　for　pressure　measurement　as　easily　as　a　clinical　thermometer　in　various　microfluidic　applications.