|Millennium:||1st millennium BC|
|Centuries:||5th century BC – 4th century BC – 3rd century BC|
|Decades:||370s BC 360s BC 350s BC – 340s BC – 330s BC 320s BC 310s BC|
|Years:||350 BC 349 BC 348 BC – 347 BC – 346 BC 345 BC 344 BC|
|347 BC by topic|
|Gregorian calendar||347 BC|
|Ab urbe condita||407|
|Ancient Egypt era||XXX dynasty, 34|
|- Pharaoh||Nectanebo II, 14|
|Ancient Greek era||108th Olympiad, year 2|
|Chinese calendar||癸酉年 (Water Rooster)
2350 or 2290
— to —
甲戌年 (Wood Dog)
2351 or 2291
|Coptic calendar||−630 – −629|
|Ethiopian calendar||−354 – −353|
|- Vikram Samvat||−290 – −289|
|- Shaka Samvat||N/A|
|- Kali Yuga||2755–2756|
|Iranian calendar||968 BP – 967 BP|
|Islamic calendar||998 BH – 997 BH|
|Minguo calendar||2258 before ROC
|Thai solar calendar||196–197|
|Wikimedia Commons has media related to 347 BC.|
Year 347 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Venno and Torquatus (or, less frequently, year 407 Ab urbe condita). The denomination 347 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years.
- In the wake of the Macedonian victory at Olynthus, Athens seeks to make peace with Macedonia. Because his financial policy is based on the assumption that Athens should not be involved in major wars, the Athenian leader, Eubulus, works for peace with Philip II of Macedon. Demosthenes is among those who support a compromise.
- An Athenian delegation, comprising Demosthenes, Aeschines and Philocrates, is officially sent to Pella to negotiate a peace treaty with Philip II. During the negotiations, Aeschines seeks to reconcile the Athenians to Macedonia's expansion into Greece.
- Coinage is introduced into Rome for the first time.
- Plato dies and his nephew Speusippus is named as head of the Academy.
- Aristotle leaves Athens due to the anti-Macedonian feeling that arises in Athens after Philip II of Macedon has sacked the Greek city-state of Olynthus in 348 BC. With him goes another Academy member of note, Xenocrates of Chalcedon. They establish a new academy on the Asia Minor side of the Aegean Sea at the newly built town of Assus.
- Plato, Greek philosopher and founder of the Academy in Athens (b. c. 427 BC)
- Eudoxus of Cnidus, Greek philosopher and astronomer who has expanded on Plato's ideas (or 355 BC) (b. 410 BC or 408 BC)