We　describe　a　facile　and　low-cost　approach　for　a　flexibly　integrated　surface-enhanced　Raman　scattering　(SERS)　substrate　in　microfluidic　chips.　Briefly,　a　SERS　substrate　was　fabricated　by　the　electrostatic　assembling　of　gold　nanoparticles,　and　shaped　into　designed　patterns　by　subsequent　lift-up　soft　lithography.　The　SERS　micro-pattern　could　be　further　integrated　within　microfluidic　channels　conveniently.　The　resulting　microfluidic　SERS　chip　allowed　ultrasensitive　in　situ　SERS　monitoring　from　the　transparent　glass　window.　With　its　advantages　in　simplicity,　functionality　and　cost-effectiveness,　this　method　could　be　readily　expanded　into　optical　microfluidic　fabrication　for　biochemical　applications.