What is the strongest pin in xiangqi?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws for movement, checkmate and both repetition rulings: a side that forces a repetition by perpetual check or perpetual chase loses rather than drawing. The chase half has not been validated against the official casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it before publishing.
Direct answer
A piece standing alone between the two generals. Stepping off their file is not merely inadvisable but illegal, because it would leave the generals facing each other. A horse, elephant or advisor there is completely frozen; a chariot, cannon or soldier can still move along the file, and nowhere else. The pinning piece is the enemy general, safely out of reach in its palace.
Turning it into material
A pinned piece is effectively undefended, because it cannot step off the file and often cannot be helped. Two ways to cash in: attack it a second time, since it cannot get out of the way; or attack the point it stands on with a piece the defender cannot afford to trade.
Breaking out of one
Move your own general off the file — there is usually a spare palace point nobody looked for — or add a second piece to the line so neither is the only thing between the generals. Counter-attack works too, if it is faster than the threat.
Related questions
Can a pinned piece give check?
Only by moving along the file it is pinned on, as a soldier stepping up to the enemy general does. A horse, elephant or advisor pinned between the generals cannot move at all.
Do ordinary pins exist too?
Yes, against chariots and cannons. Cannon pins work backwards, because the pinned piece is the cannon's screen.
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