The invention provides a P (Positive) type insert layer with a cycle structure and a growing method. An epitaxial structure of the P type insert layer comprises a substrate, a low-temperature GaN buffer layer, a GaN undoped layer, an N (Negative) type GaN layer, an MQW (Multiple Quantum Well) structure, a low-temperature P type GaN layer, a P type AlGaN layer, a high-temperature P type GaN layer and a P type contact layer in sequence from bottom to top; the growing method of the P type insert layer comprises the following specific steps that a PAlGaN / PinGaN cycle structure layer grows; the structure comprises three to ten structures that PGaN and PInGaN grow in an overlapping way; the growth is divided into two steps, i.e. growing an Al component to gradually raise the PAlGaN layer at first, and after the completion of growth that the PAlGaN layer is gradually raised along with the Al component, growing the PInGaN layer, and then continuously growing six PAlGaN layer / PInGaN layer cycles. According to the P type insert layer and the growing method, the dislocation density of PGaN can be decreased, and the crystalline quality can be improved; in addition, the generation of non-radiating load centers is inhibited, and the injection efficiency of cavities is improved, so that the light emitting efficiency of a gallium-nitride-based LED (Light Emitting Diode) is improved; thirdly, the diffusion of Mg atoms towards an active area is reduced, so that the internal quantum efficiency is improved.