Abstract: The effect of submicron-sized Al2O3 particle addition on the crystal structure and superconducting properties of YBa2Cu3O7-δ ceramics was systematically studied. Series of YBa2Cu3O7−δ + x Al2O3 samples (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5,0.6 wt.% ) were prepared using the solid state reaction method. The lattice parameters and the orthorhombicity were decreased slightly with Al2O3 addition. No change in the structural symmetry state was obtained. SEM micrographs revels the decreasing trend in the grain size of the composite samples. The superconducting transition temperatures (Tc) determined by standard four-probe method was decreased and dropped sharply with higher alumina content. Excess conductivity fluctuation analysis using Aslamazov-Larkin model fitting reveals transition of two dominant regions (2D and 3D) above Tc. The decrease in 2D-3D crossover temperature i.e. Lawerence-Doniach temperature in the mean field region has been observed as a consequent dominance of 3D region to increase in wt. % of Al2O3 in the composite.