Y2O3:Eu3+ phosphors with 3-dimensional assembled gear-shaped submicrostructure were successfully synthesized through a controlled solvothermal approach followed by a subsequent heat treatment, without using any catalyst or template. These gear-shaped prisms expressed pretty good size distribution. Besides, the possible formation mechanism of the gear-shaped prisms was discussed in brief. Furthermore, their photoluminescence (PL) properties were investigated. The results indicated that the gear-shaped prism samples showed the strongest red emission corresponding to 5D0→7F2 transition (609 nm) among the synthesized samples, implying better photoluminescence property of this submicrostructure with ordered arrays, and suggesting potential application in optoelectronics, such as for fluorescent lamps and flat panel devices application, etc.