In this paper, in order to investigate the heat transfer characteristics of three-dimensional nanofluid jet microchannel (NJMC), the two-fluid model based on Euler's method coupled with the turbulence model is used to numerically simulate the Al2O3-desionized water jet impingement cooling process, and the results of the study show that the inlet flow rate of the nanofluid can strengthen the degree of its jet focusing and enhance the performance of heat transfer. In this paper, it is also found that the hemispherical micro-rib and side-flow orifices in the nanofluid array jet microchannel (NAJMC) can effectively strengthen the longitudinal vortex and slow down the velocity drift, and the nested micro-rib can effectively reduce the irreversible loss in the flow of nanofluid, and all three of them can make the heat transfer performance of the NAJMC go up. Therefore, in this paper, a nanofluid composite jet microchannel (NCJMC) is designed and numerically simulated, and the entropy production theory is used to analyze and evaluate the heat transfer performance of MCJMC, and it is found that the heat transfer performance of NCJMC is significantly improved compared with that of NAJMC. When the inlet flow rate is the same, its Nu and PEC are increased by 21.3% and 60.0%, respectively, compared with MAJMC, and the total entropy production is reduced by 38.0%.