Hi,everyone ,i am new , when i run kernel on AT91SAM9261EK, at starting kernel, it is stop, my kernel is linux-2.6.20 and uboot is u-boot-1.1.5

copy your serial output logs, too.

the serial output logs is

Hit any key to stop autoboot: 0
## Booting image at 20008000 ...
Image Name:
Image Type: ARM Linux Kernel Image (gzip compressed)
Data Size: 1298697 Bytes = 1.2 MB
Load Address: 20008000
Entry Point: 20008040
Verifying Checksum ... OK
Uncompressing Kernel Image ... OK

Starting kernel ...

when begin starting kernel, it is stop here

do you load your kernel image to 20008000? The kernel image is extracted and extracting destination should be different. Having the source and destination at the same memory area, strange things happen (it sometimes works, but not with all images).
Does your kernel have the serial port support compiled in at all? Does it have the right serial port as the console port defined on command line (u-boot parameter bootargs; kernel argument like console=ttyS0,11500). ttyS0 should be the default. If you have configured the kernel to use atmel's serial device major/minor numbers in menuconfig, use console=ttyAT0,115200. Check your bard file (arch/arm/mach-at91/board-*.c) that you have enabled the dbgu and mapped to serial port #0.

please post your uboot's printenv output too