Abstract: Wet etching deep pits or grooves,required for metallization such as electroplating,on Pyrex 7740,is studied.In the wet etching experiment,HF:HNO₃:H₂O as etching solution,and Cr/Pt or Cr/Au sputtering deposited,in combination with photoresist（PR）,as etching mask,were investigated. The experiment has shown that Cr/Pt/PR（30nm/300nm/15μm） was found to be ideal etching mask for etching pits required for metallization.The etched pits,in depth of near 28μm,with smooth surface and small ratio（about 1.34:1） of undercut to deepness,were obtained.And,in these etched pits,Cu pads for soldering were successfully electroplated.These experiment results can be used to fabricate high ratio aspect of grooves in some micro fluid devices.