Who moves first 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
Red moves first, always. This is fixed by the rules rather than decided by colour preference, and in diagrams Red is conventionally shown at the bottom. In tournaments, who plays Red is decided by draw or by pairing rules.
How big is the first-move advantage?
Real, and usually described as smaller than in chess, though how large it is depends on the era and the level. Red's practical advantage is the right to choose the opening system — playing 炮二平五 on move one forces Black to answer a specific threat.
At club level the advantage is almost invisible next to the effect of a single missed tactic.
Why red and black rather than white and black
Red is the auspicious colour in Chinese culture, and the pieces are traditionally red and black ink on wood. Some sets use green or blue instead of black; the side that moves first is still the red one.
Related questions
Can Black choose to move first?
No. The rule is fixed. If you want the first move, you want to be Red, and that is decided before the game.
Does Red win more often?
Slightly, at master level. The gap is smaller than White's in chess, and below expert level it is swamped by everything else.