Constructing functional nanoprobes with high conversion efficiency is the key to promote the development of photoacoustic molecular imaging. With the development of photoacoustic molecular imaging, selfassembled nanoprobes with nonlinear enhancement of photoacoustic conversion efficiency have gradually become a research hotspot. However, quantitative studies on nonlinear enhancement of nanoprobes have not been reported. In this work, by taking gold nanospheres as an example, the nonlinear photothermal and photoacoustic effects induced by selfassembly of metal nanoprobes are quantitatively investigated by finite element simulation, and the enhancement rule of photoacoustic effects of selfassembly nanoprobes is revealed, which lays a theoretical foundation for the construction of photoacoustic selfassembly nanoprobes with high conversion efficiency.