If you mean the fruit “orange”

• Yes, oranges (the citrus fruit) are generally allowed in a Jain diet.
• Eat fresh, well‑washed fruit, check for insects, and avoid cutting/storing for long.
• Avoid eating at night; if taking juice, strain it and have it only in daylight.
• During Paryushan/strict vows, some follow stricter rules and may avoid sour fruits; follow your declared vrata and local updesh.

If you meant “orange” as a color for clothes

• Jain monks do not wear saffron/orange robes (Śvetāmbara wear white; Digambara are sky‑clad).
• Lay Jains may wear any simple, modest color, including orange.

If you meant “orange vegetables” like carrot

• Carrot is a root vegetable and is traditionally avoided by Jains (year‑round by stricter followers, and at least during Paryushan by many).