issues for display

I cannot see from the HDMImonitor aftert plug the HDMI cable into the TX1,can someone tell me how to solve the problem?

Which release are you using (has it been flashed yet)? The default release wasn’t too reliable, the newer release is better. See this if you haven’t already flashed (you probably have to log in there and then hit this link again to see it):
https://developer.nvidia.com/embedded/linux-tegra

If the monitor purely HDMI? Are there any adapters?

Assuming this is purely HDMI you should be able to still have access for debugging via ssh (your router should show the address…you can log in via user/pass of either “ubuntu”/“ubuntu” or “nvidia”/“nvidia”) or serial console (this is always logged in to user “nvidia”). For serial console, see:
http://www.jetsonhacks.com/2015/12/01/serial-console-nvidia-jetson-tx1/

HDMI is hot-plug, so it is also possible that either of these will get you temporary GUI access:

  • Unplug and replug the connector.
  • Start with no HDMI connected, wait about 2 minutes, then plug in the HDMI.

You might also get text-mode console via CTRL-ALT-F2 key combination.

If you have access, then you might be interested in this (this is listed under TX2, but TX1s have much in common since they started sharing the same kernel and rootfs):
https://elinux.org/Jetson_TX2/r28_Display_debug

I am using the JetPack3.1 ,and i use a HDMI to VGA convert cable,but i can see nothing in the screen.

The VGA converter cannot work as intended. The wire used for plug-n-play on video did not exist with that type of connector. There are cases where people get lucky and a default mode works with that monitor.

HDMI is hot plug, so you can unplug and re-plug at any time. If you do have an HDMI monitor with the same specs, and you plug that in to get a setting going, then unplug the true HDMI monitor followed by plugging in the VGA monitor, then the old settings will still be present since VGA is not detected as a new device (at least the EDID data never changes from the previous monitor).