INCOME TAX - Changes in valuation allowance (Details) - CNY (¥)	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
INCOME TAX
Balance at the beginning of the year	¥ 140,255,931	¥ 107,782,306	¥ 40,764,285
Additions	31,752,295	32,473,625	68,593,841
Reduction	(25,063,570)		(1,575,820)
Balance at the end of the year	¥ 146,944,656	¥ 140,255,931	¥ 107,782,306

Amount of decrease in the valuation allowance for a specified deferred tax asset.

No definition available.

Name:	niu_ValuationAllowanceDeferredTaxAssetDecreaseAmount
Namespace Prefix:	niu_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

+ Details

Name:	us-gaap_DeferredTaxAssetsValuationAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

Name:	us-gaap_IncomeTaxDisclosureAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-2

+ Details

Name:	us-gaap_ValuationAllowanceDeferredTaxAssetChangeInAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration