Most　of　the　current　pitch　detection　algorithms　can　not　work　well　under　the　high　noise　environment.　For　this　reason,　a　pitch　detection　algorithm　for　noisy　speech　signal　based　on　pre-filtering　and　weighted　wavelet　coefficients　is　proposed.　Firstly,　the　noisy　speech　signals　are　pre-filtered.　Secondly,　the　speech　pre-filtered　is　decomposed　by　the　quadratic　spline　wavelet.　Thirdly,　the　wavelet　coefficients　of　three　consecutive　scales　are　weighted　to　emphasize　the　sharp　change　points.　Fourthly,　three　candidate　pitch　periods　are　extracted　from　the　weighted　signals.　Finally,　the　pitch　period　is　calculated　by　autocorrelation　function.　Experiments　show　that　this　algorithm　can　increase　the　performance　of　pitch　detection　in　noisy　environment　and　decreases　computational　complexity　compared　with　DWT-NCCF　method.　©　2008　IEEE.