I know how to fix it now. When i login, i installed lilo in the debian system, after that, use liloconfig to configure it, therefor, liloconfig will add my debian and windows entrance to lilo.conf. Ok, i just mount my slack partition and follow astrogeek's guideline to add a entry for slackware, all the things work well now.
but, i get delete the map line, otherwise there would be an error which says 'Syntax error at or above line 75 in file "/etc/lilo.conf"。so, i simply delete the map line, then it can work, but gets a warning like 'The boot sector and the map file have *NOT* been altered', i installed it, and it can lead me to my debian and slackware well. Then i login my slackware and installed lilo again, all the things were then same.
my debian entrance like:
image = /mnt/hd/debian/boot/vmlinuz
root = /dev/hda9
initrd = /mnt/hd/debian/boot/initrd.img
#map = /mnt/hd/debian/boot/coffee.bmp
label = Debian
*: I had copy a new file with a short filename from the old ones.