Platinum　particles　were　electrochemically　deposited　on　glassy　carbon　electrodes　modified　by　carbon　nanotubes.　The　chemically　modified　glassy　carbon　electrodes　with　platinum　particles　and　carbon　nanotubes　(Pt/CNTs/GCE)　were　used　as　formaldehyde　sensors.　Electrochemica1　behaviors　of　formaldehyde　at　Pt/CNTs/GCE　were　investigated　by　cyclic　voltammetry　(CV)　and　linear　scan　voltammetry　(LSV).　Experimental　conditions　were　optimized,　and　a　voltammetric　method　for　determining　formaldehyde　was　developed.　The　experimental　results　show　that　the　optimum　accumulation　potential　is　-0.1　V　and　the　optimum　accumulation　time　is　180　s.　A　highly　linear　response　to　formaldehyde　in　the　concentration　range　of　8.0mol/L-1.0　mmol/L　was　observed　in　0.01　mol/LH2SO4,　with　a　detection　limit　of　3.0mol/L　estimated　at　a　signal-to-noise　ratio　of　3:1.　The　presented　method　of　determining　formaldehyde　exhibits　high　sensitivity　and　good　reproducibility.