Maintenance Margin is the minimum margin required to continue holding a position.
It will increase or decrease depending on the trader's trading volume. Liquidation occurs when the isolated margin for the position is less than its maintenance margin level.
Trader place a long position of 1 BTC at USD 10,000 with 50x leverage (Isolated Margin)
Initial Margin = (1 * 10000) / 50 = 200 USDT
Maintenance Margin = 1 * 10000 * 0.1% = 10 USDT
This means that this position could take an unrealized loss (Mark Price) of up to 190 USDT (200 USDT – 10 USDT) before liquidation takes place.