Eleetroless NiP coating has stochastic nonlinear structure, which was in far from equi-librium and instability state. Fractal theory, an effective method for solvin9 nonlin-ear system, was introduced to describe the coating structure quantitatively. Disorderand self-similarity characteristics, which a~ the two basic features of fractal, were plained in this paper for the first time. The results show that amorphous NiP structuexhibits scale invariance and can be quantitatively characterized by ]rectal dimension.Based on the fractal principte a two-dimensional computer simulation on electrolessNiP deposition was carried out and it is in agreement with the experimental Tsult. Fi-nally, the fractal dynamics and process of atom growth were investigated. The resultsshow that the atom deposition is reaction limited growth process.