The Zen tradition of Buddhism doesn’t use many symbols, if by “symbol” you mean a visual representation of some mental state or experience.
Zen altars typically have the following, which can be viewed as symbolic:
- Statue of Buddha, to remind meditators of the Buddha inside of each of them
- Representations of the 4 Elements: incense (air), candles (fire), water container (water), and rice (earth)
- Flowers, in celebration of the gift of life
Zen robes are based on Chinese Taoist robes, not traditional South Asian robes, in reflection of the influence of Taoism on the Zen tradition. Zen priests wear a kasa/kesa — a bib-like piece of cloth that represents the early robes worn in Buddha’s time.
Occasionally a Zen hall will have images of Kuan Yin (the bodhisattva of compassion) or another bodhisattva, to remind practitioners of the bodhisattva energy that exists within each of them.
The rest of the Zen hall is focused on the practice of meditation, which is non-symbolic.
At Zen temples in Asia, you’ll see the 10 Oxherding Pictures painted on the outside of buildings. These pictures are symbolic of one’s experiences in meditation.
In Asia, you’ll also see the Dharmacakra painted outside of buildings. This is the traditional representation of the 8-Fold Path.
Finally, in Asia you’ll see dragons painted on buildings and carved into the roof substructures of temple buildings. Dragons represent our Buddha-seeking energy.
Note: the yin/yang symbol referred to by another answerer is actually a Taoist symbol, not one from the Buddhist tradition.

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