Response.Clear();
Response.Buffer = true;
Response.ContentType="application/vnd.ms-excel";
Response.AddHeader("Content-disposition", "attachment; filename=BillingInformation_"+this.DDL_Mode.SelectedValue+"("+System.DateTime.Now.ToString("yyyyMMdd")+").CSV");
Response.ContentEncoding=System.Text.Encoding.UTF7;
Response.Charset="";
Response.Write("Export Excel File To Clients sample");
Response.End();
HTTP头信息 文件类型对照

ai application/postscript
aif audio/x-aiff
aifc audio/x-aiff
aiff audio/x-aiff
asc text/plain
au audio/basic
avi video/x-msvideo
bcpio application/x-bcpio
bin application/octet-stream
bmp image/bmp
cdf application/x-netcdf
class application/octet-stream
cpio application/x-cpio
cpt application/mac-compactpro
csh application/x-csh
css text/css
dcr application/x-director
dir application/x-director
djv image/vnd.djvu
djvu image/vnd.djvu
dll application/octet-stream
dms application/octet-stream
doc application/msword
dvi application/x-dvi
dxr application/x-director
eps application/postscript
etx text/x-setext
exe application/octet-stream
ez application/andrew-inset
gif image/gif
gtar application/x-gtar
hdf application/x-hdf
hqx application/mac-binhex40
htm text/html
html text/html
ice x-conference/x-cooltalk
ief image/ief
iges model/iges
igs model/iges
jpe image/jpeg
jpeg image/jpeg
jpg image/jpeg
js application/x-javascript
kar audio/midi
latex application/x-latex
lha application/octet-stream
lzh application/octet-stream
m3u audio/x-mpegurl
man application/x-troff-man
me application/x-troff-me
mesh model/mesh
mid audio/midi
midi audio/midi
mif application/vnd.mif
mov video/quicktime
movie video/x-sgi-movie
mp2 audio/mpeg
mp3 audio/mpeg
mpe video/mpeg
mpeg video/mpeg
mpg video/mpeg
mpga audio/mpeg
ms application/x-troff-ms
msh model/mesh
mxu video/vnd.mpegurl
nc application/x-netcdf
oda application/oda
pbm image/x-portable-bitmap
pdb chemical/x-pdb
pdf application/pdf
pgm image/x-portable-graymap
pgn application/x-chess-pgn
png image/png
pnm image/x-portable-anymap
ppm image/x-portable-pixmap
ppt application/vnd.ms-powerpoint
ps application/postscript
qt video/quicktime
ra audio/x-realaudio
ram audio/x-pn-realaudio
ras image/x-cmu-raster
rgb image/x-rgb
rm audio/x-pn-realaudio
roff application/x-troff
rpm audio/x-pn-realaudio-plugin
rtf text/rtf
rtx text/richtext
sgm text/sgml
sgml text/sgml
sh application/x-sh
shar application/x-shar
silo model/mesh
sit application/x-stuffit
skd application/x-koan
skm application/x-koan
skp application/x-koan
skt application/x-koan
smi application/smil
smil application/smil
snd audio/basic
so application/octet-stream
spl application/x-futuresplash
src application/x-wais-source
sv4cpio application/x-sv4cpio
sv4crc application/x-sv4crc
swf application/x-shockwave-flash
t application/x-troff
tar application/x-tar
tcl application/x-tcl
tex application/x-tex
texi application/x-texinfo
texinfo application/x-texinfo
tif image/tiff
tiff image/tiff
tr application/x-troff
tsv text/tab-separated-values
txt text/plain
ustar application/x-ustar
vcd application/x-cdlink
vrml model/vrml
wav audio/x-wav
wbmp image/vnd.wap.wbmp
wbxml application/vnd.wap.wbxml
wml text/vnd.wap.wml
wmlc application/vnd.wap.wmlc
wmls text/vnd.wap.wmlscript
wmlsc application/vnd.wap.wmlscriptc
wrl model/vrml
xbm image/x-xbitmap
xht application/xhtml+xml
xhtml application/xhtml+xml
xls application/vnd.ms-excel
xml text/xml
xpm image/x-xpixmap
xsl text/xml
xwd image/x-xwindowdump
xyz chemical/x-xyz
zip application/zip

来源:网络