根据官方的提示，下载的img镜像需要转换为vmdk。
地址：http://wiki.openwrt.org/doc/howto/vmware
转换需要qemu-utils，网上的安装方法：
#64位系统 centos 6.x
wget http://pkgs.repoforge.org/qemu/qemu-0.15.0-1.el6.rfx.x86_64.rpm
wget http://pkgs.repoforge.org/qemu/qemu-img-0.15.0-1.el6.rfx.x86_64.rpm
rpm -ivh qemu-0.15.0-1.el6.rfx.x86_64.rpm
rpm -ivh qemu-img-0.15.0-1.el6.rfx.x86_64.rpm
如果是centos5.X 64位就下载qemu-0.14.1-2.el5.rfx.x86_64.rpm，32位下载qemu-0.14.1-2.el5.rfx.i386.rpm。
centos6.X 32位下载qemu-0.15.0-1.el6.rfx.i686.rpm
其实只要 yum install qemu* 就好了
Dependencies Resolved ================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
qemu x86_64 :0.15.-.el6.rfx /qemu-0.15.-.el6.rfx.x86_64 M
qemu-img x86_64 :0.15.-.el6.rfx /qemu-img-0.15.-.el6.rfx.x86_64 k
Installing for dependencies:
SDL x86_64 1.2.-.el6 base k
audiofile x86_64 :0.2.-11.1.el6 base k
bluez-libs x86_64 4.66-.el6 base k
celt051 x86_64 0.5.1.3-.el6 base k
esound-libs x86_64 :0.2.-3.1.el6 base k
spice-server x86_64 0.12.-.el6 base k
下一步，转换文件：
gunzip openwrt-x86-generic-combined-ext4.img.gz
qemu-img convert -f raw openwrt-x86-generic-combined-ext4.img -O vmdk openwrt-x86-generic-combined-ext4.vmdk
sz openwrt-x86-generic-combined-ext4.vmdk