Pattern

Regex for Chinese citizen ID

18-character Chinese national ID.

The Chinese citizen ID regex is ^\d{17}[\dXx]$ — copy it below, or open it in the explainer for a token-by-token breakdown.

The pattern

^\d{17}[\dXx]$

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Token-by-token breakdown

Every part of the pattern, left to right:

Token	Meaning
`^`	start of string (or line in multiline mode)
`\d{17}`	exactly 17 times: digit (0–9)
`[\dXx]`	any of: digits (0–9), “X”, “x”
`$`	end of string (or line in multiline mode)

About this pattern

Country-specific identifier formats vary widely. The pattern below validates structure; many real IDs include checksums that regex can't verify. For high-stakes use, validate against the issuing authority.

Quick usage in different languages

This exact pattern — with the correct escaping and idioms for each language:

JavaScript: /^\d{17}[\dXx]$/.test(value)
Python: re.match(r"^\d{17}[\dXx]$", value)
Java: Pattern.compile("^\\d{17}[\\dXx]$").matcher(value).matches()
C# / .NET: Regex.IsMatch(value, @"^\d{17}[\dXx]$")
Go: regexp.MustCompile(`^\d{17}[\dXx]$`).MatchString(value)
Ruby: /^\d{17}[\dXx]$/.match?(value)
PHP: preg_match('~^\d{17}[\dXx]$~', $value)

The explainer’s Code tab regenerates these for any pattern you paste, and the downloadable cheat sheet bundles the breakdown, all seven snippets, and the pitfalls below onto one printable page.

Common pitfalls

Anchored to the whole string. This pattern uses ^ and $, so it requires the entire input to match. To find it inside a longer text, drop the anchors and use the global (g) flag.
Escape it correctly per language. In Java and JavaScript strings each backslash must be doubled (\\d); in Python, Go, and C# use raw/verbatim strings so the backslashes survive.
Validate beyond format. Matching the format doesn't guarantee the value is real. Confirm the chinese citizen id against a source of truth (database, API, or checksum) where it matters.

Related patterns

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