| Sijiu | |
| Official Name: | 四九镇 |
| Settlement Type: | Town |
| Pushpin Map: | China Guangdong |
| Pushpin Label Position: | top |
| Subdivision Type: | Country |
| Subdivision Name: | China |
| Subdivision Type1: | Province |
| Subdivision Name1: | Guangdong |
| Subdivision Type2: | Prefecture-level city |
| Subdivision Name2: | Jiangmen |
| Subdivision Type3: | County-level city |
| Subdivision Name3: | Taishan |
| Unit Pref: | metric |
| Area Footnotes: | [1] |
| Area Total Km2: | 260 |
| Population Total: | 43000 |
| Population Density Km2: | auto |
| Timezone: | China Standard |
| Utc Offset: | +8 |
| Coordinates: | 22.212°N 112.8632°W |
| Postal Code Type: | Postal code |
| Postal Code: | 529222 |
| Area Code: | 0750[2] |
Sijiu is a town in the southwest Guangdong Province in Southern China. It is under the administration of Taishan County in Jiangmen Prefecture.[1] As of 2014, the population included about 50,000 "foreigners", mainly from Hong Kong, Macao, and Taiwan.[1] About 50 "foreign" businesses are established here, including 20 Taiwanese enterprises involved in light manufacturing located along what is known locally as the "Taiwanese Merchant Street".[1]
Sijiu is the atonal pinyin romanization of the Standard Mandarin pronunciation Sījiù of the Chinese name Chinese: {{linktext|四九, meaning "4-9" or "4th-&-9th", from locals' previous custom of gathering for trade in the town on the 4th and 9th days of the months of the traditional lunisolar calendar. The same name was previously written Ssu-chiu in Wade-Giles romanization and is written as Sei³ Gau² in the Jyutping romanization of its Cantonese pronunciation.