How to excite the nonlinear optical effect in the case of low threshold (mW or pJ order) and small scale (μm or less) is a topic field of optical research in recent years. The most direct application requirement is photonic integrated circuit, which is the foundation to realize the ultra-high speed and large capacity information network in the future. Photonic crystals (PCs) have the photonic band gap (PBG) just like the semiconductor band for elec-tronics, so it is known as "photonic semiconductors". PCs provide a novel and practical means of manipulating photons, therefore the possibility of photonic integrated circuit with low threshold arises. More and more nonline-ar effects have been found in PCs, such as photonic crystal slow light, the band gap soliton, electromagnetic in-duction transparency, second harmonic generation and optical bistability. This paper will focus on the summaries of some major achievements and advances about PCs that would promote the nonlinear photonic integrated de-vices. Certainly the related applications will be introduced and the future outlook of the nonlinear PCs will be discussed.