---
title: "What Is a Hollow Cannon (空頭炮) in Xiangqi? · Xiangqi Master"
description: "空頭炮 is a cannon on the general's file with the line completely clear between them — a powerful positional threat, not an immediate check."
url: https://xiangqimaster.com/blog/what-is-a-hollow-cannon
updated: 2026-09-22
source: Xiangqi Master (https://xiangqimaster.com)
license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
---

# What is a hollow cannon (空頭炮)?

These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.

> Direct answer
>
> **空頭炮** — "hollow-head cannon" — is a cannon on the enemy general's file with **nothing at all between them**. It gives no check, because a cannon needs a screen. What it does is far worse for the defender: the general can never move onto that file, and **any piece that steps onto the line becomes a screen** and is instantly attacked.

## Why it is so unpleasant to face

It freezes a whole file. The defender cannot interpose anything without handing over a target, cannot let the general use the file, and often cannot remove the cannon. Many attacks are built by establishing 空頭炮 first and then bringing a second piece.

## Getting rid of one

The usual answers are to capture the cannon, to block the file with a piece that is *defended* so being a screen costs nothing, or to move the general off the file if it can. The one thing that does not work is blocking with an undefended piece.

## Related questions

Is a hollow cannon giving check?

No. With an empty line there is no capture available, therefore no check.

Is it stronger than a cannon with a screen?

Different. A screened cannon threatens now; a hollow cannon paralyses the file and threatens everything that later steps onto it.

## Related xiangqi resources

How the cannon moves

Captures only by jumping exactly one screen

Attacking the palace

How xiangqi attacks are built

Xiangqi glossary

Every term, with the Chinese and the WXF spelling

## Try it on a real board

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