A　disposable　and　sensitive　electrochemical　aptasensor　was　developed　based　on　a　single-stranded　DNA　(ssDNA)-methylene　blue　(MB)　complex　for　the　determination　of　bisphenol　A　(BPA).　BPA-specific　aptamer,　a　ssDNA　with　hairpin　structure,　was　immobilized　on　a　low-cost　plastic　electrode　and　acted　as　both　the　bio-recognition　element　and　the　signal-amplification　platform.　MB　was　then　intercalated　into　the　aptamer　and　acted　as　the　signaling　probe.　The　intercalated　MB　was　liberated　upon　interaction　with　BPA　due　to　DNA　conformational　change,　thereby　resulting　in　the　reduction　of　electrochemical　response.　The　proposed　sensors　in　the　intermediate　and　final　stages　were　carefully　characterized.　Under　optimal　conditions,　a　good　linear　relationship　was　presented　with　the　logarithm　of　BPA　concentrations　in　the　range　of　0.001-100　mu　g/L,　and　a　detection　limit　of　0.4　ng/L　was　obtained.　This　proposed　sensor　was　applied　to　detect　BPA　in　real　samples　and　achieved　satisfying　results.