In this paper, we propose to use fuzzy fusion rules to improve the performances of the CA-CFAR and OS-CFAR detectors for non-coherent MIMO radars in homogenous and non-homogenous Pareto background. First, the membership function for each individual detector is computed. At the fusion center, the membership functions are combined using four fuzzy fusion rules, namely; the “MIN”, “MAX”, “algebraic product” and the “algebraic sum” to yield a binary decision after defuzzification. The obtained results show that for a number of nodes equal to four, the performance is the best for a high number of receivers. In homogeneous background, the “algebraic product” fusion rule gives the best result when SCR > 4 dB whereas the “algebraic sum” is the best when SCR < 4 dB for the CA-CFAR. For the OS-CFAR, it is clearly shown that the “algebraic product” is the best. In non-homogenous case, the “algebraic sum” fusion rule gives the best results for the CA-CFAR, and the “algebraic product” for the OS-CFAR.