| Official Name: | Lang Suan |
| Native Name: | หลังสวน |
| Native Name Lang: | th |
| Settlement Type: | District |
| Subdivision Type: | Country |
| Subdivision Name: | Thailand |
| Subdivision Type1: | Province |
| Subdivision Name1: | Chumphon |
| Subdivision Type2: | Seat |
| Subdivision Name2: | Khan Ngoen |
| Subdivision Type3: | Tambon |
| Subdivision Type4: | Muban |
| Established Title: | District established |
| Population Total: | 70837 |
| Population As Of: | 2007 |
| Blank Name Sec1: | Postal code |
| Blank Info Sec1: | 86110 |
| Blank Name Sec2: | Geocode |
| Blank Info Sec2: | 8604 |
| Timezone: | ICT |
| Utc Offset: | +7 |
| Coordinates: | 9.9456°N 99.0786°W |
Lang Suan (Thai: หลังสวน, in Thai pronounced as /lǎŋ sǔa̯n/) is a district (amphoe) of Chumphon province, southern Thailand.
Lang Suan was originally a mueang reporting directly to Bangkok. During the Thesaphiban reforms at the end of the 19th century it was put under monthon Chumphon. On 29 April 1917 the district's name was changed from Mueang Lang Suan to Khan Ngein (ขันเงิน).[1] On 1 April 1932 the province was abolished and its districts were incorporated into Chumphon province.[2] On 14 November 1938 the district's name was changed to Lang Suan (หลังสวน).[3]
Neighboring districts are (from the south clockwise) Lamae and Phato of Chumphon Province, La-un of Ranong province, and Sawi and Thung Tako of Chumphon. To the east is the Gulf of Thailand.
The main river of the district is the Lang Suan.
The district is divided into 13 sub-districts (tambons), which are further subdivided into 147 villages (mubans). The town (thesaban mueang) Lang Suan includes the tambon Lang Suan and parts of Khan Ngoen, Pho Daeng, Laem Sai, and Wang Tako. The sub-district municipality (thesaban tambon) Paknam Lang Suan includes tambon Pak Nam. There are a further 12 tambon administrative organizations (TAO).
| No. | Name | Thai | Villages | Pop. | |
|---|---|---|---|---|---|
| 1. | Lang Suan | หลังสวน | - | 3,914 | |
| 2. | Khan Ngein | ขันเงิน | 7 | 7,460 | |
| 3. | Tha Maphla | ท่ามะพลา | 9 | 3,090 | |
| 4. | Na Kha | นาขา | 13 | 7,768 | |
| 5. | Na Phaya | นาพญา | 19 | 5,017 | |
| 6. | Ban Khuan | บ้านควน | 17 | 7,859 | |
| 7. | Bang Maphrao | บางมะพร้าว | 14 | 4,628 | |
| 8. | Bang Nam Chuet | บางน้ำจืด | 14 | 4,851 | |
| 9. | Paknam | ปากน้ำ | 6 | 6,843 | |
| 10. | Pho Daeng | พ้อแดง | 10 | 2,237 | |
| 11. | Laem Sai | แหลมทราย | 12 | 3,694 | |
| 12. | Wang Tako | วังตะกอ | 13 | 7,285 | |
| 13. | Hat Yai | หาดยาย | 13 | 6,191 |