The　single-phase　flow　and　droplet　flow　are　investigated　in　a　rectangular　microchannel　with　a　T-junction,　through　experiments　and　simulations　to　improve　the　understanding　of　a　droplet　flow　and　its　effect　on　overall　flow　in　channels　with　junctions.　Droplet　behavior　can　be　divided　into　three　modes:　flow　into　the　side　branch,　a　split　at　the　junction,　and　flow　into　the　downstream　channel.　In　branches　of　the　junction,　the　flow　rate　ratio　and　the　pressure　difference　are　affected　by　droplets　with　the　same　flow　behavior　flowing　in　the　junction.　The　change　in　the　volumetric　flow　rate　ratio　and　pressure　difference　between　two　channels　also　depend　on　droplet　size　and　flow　conditions.　Furthermore,　the　length　of　the　droplet　affects　whether　the　droplet　splits　at　the　junction,　and　this　behavior　can　be　documented　by　a　power　law　relationship　between　the　capillary　number　Ca　and　droplet　length.