> For the complete documentation index, see [llms.txt](https://support.backpack.exchange/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://support.backpack.exchange/support-docs/cn/jiao-yi-suo/jiao-yi/ding-dan-lei-xing/xian-jia-dan.md).
# 限价单
**限价单 (Limit Order)** 允许你在买入时设定你愿意支付的最高价格，或在卖出时设定你愿意接受的最低价格。
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### 何时使用？
* 当你想要控制确切的进场或出场价格时。
* 适合耐心等待有利市场条件的交易者。
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### 关键点
成交并不保证 —— 只有当市场价格达到或超过你设定的价格时，订单才会被执行。
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### 为什么我的限价单最终会以市价单的方式成交？
* 限价单的逻辑是：
* 买单 (buy order) 会在 **≤ 你设定的价格** 时成交。
* 卖单 (sell order) 会在 **≥ 你设定的价格** 时成交。
* 如果你 **未启用 Post Only** 选项，系统会在满足价格条件的情况下，立即将你的订单与订单簿中的现有订单匹配。
* 若要确保你的订单始终作为 **挂单 (Maker order)** 被放入订单簿，你需要勾选 **Post Only**。否则，你的订单可能会立即作为 **吃单 (Taker order)** 被执行。
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**示例 (Example):**
* 你在 30,000 设置了一笔 **BTC/USD 买入限价单 (buy limit order)**。
* 当前最佳卖价是 29,900。
* **结果 (Result):** 系统会立即在 29,900 执行该订单，而不是挂在 30,000 等待。
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