Structure:

Adj + Adj + 的 (+ Noun)

Another way of putting that (and we’ll be using this form more extensively below) is:
A A + 的 (+ Noun)

Meaning:

If an adjective is only one syllable (one character), then reduplicating it is a no-brainer. In most Chinese textbooks and grammar books, this is known as the “AA” pattern

Examples:

1. 果汁 甜甜的。

    Guǒzhī tiántiánde

    Fruit juice is sweet.

2. 妈妈的手 暖暖的。

    Māmɑdeshǒu nuǎnnuǎnde

    Mother’s hands are warm.

3. 你的 脸 红红的。

    Nǐde liǎn hónɡhónɡde

    Your face is red.

Two-Syllable Adjectives (AABB)

Structure:

If the adjective has more than one character, then you should repeat each character individually (rather than the whole word). This is known as the “AABB” pattern

Meaning:

A A B B + 的 (+ Noun)

Examples:

1. 干净 → 干干净净

    ɡānjìnɡ → ɡānɡānjìnɡjìn

    clean

2. 高兴 → 高高兴兴

    ɡāoxìnɡ → ɡāoɡāoxìnɡxìn

    happy

3. 热闹 → 热热闹闹

    rènɑo → rèrènɑonào

    happy

4. 开心 → 开开心心

    kāixīn → kāikāixīnxī

    happy

Using Reduplicated Adjectives as Adverbs (AABB)

Structure:

A A B B + 地 + Verb

Meaning:

When adjectives are used as adverbs to modify verbs, you can reduplicate the adjective using the AABB pattern.