Hi.
I solve my problem.
Solution found in this topic:
Once kmod-fs-ntfs exists, ntfs-3g doesn't work. So just remove kmod-fs-ntfs.
and reboot router!
Now USB-HDD is readwrite mode and successfuly automounting after plugging:
root@OpenWrt:~# mount | grep mnt
/dev/sdb1 on /mnt/sdb1 type fuseblk (rw,relatime,user_id=0,group_id=0,allow_other,blksize=4096)
and my /etc/rc.local is empty because working 'block mount' in /etc/init.d/fstab .
Now I need add tab "Safe Eject USB" in LUCI interface to execute command "/etc/init.d/fstab stop" .
Is it possible ?